20dfvdvf

STAR CHARTS AND OBSERVING TIPS FOR LATE FALL NOVEMBER/DECEMBER 2017

The Canadian

Magazine of Astronomy & Stargazing

FAREWELL TO

SATURN Spectacular images from Cassini’s groundbreaking 13-year mission

2017 TOTAL ECLIPSE Reader reports and sensational photos

GEMINID METEORS: Don’t miss them!

NIGHT SKY PHOTOS Choosing the right lens

REVIEW Orion’s motorized StarBlast scope 1

SKYNEWS

• NOVEMBER/DECEMBER 2017

visit skynews.ca Saturn and itS magnificent ringS aS imaged by caSSini

NOVEMBER/DECEMBER 2017 • SKYNEWS

1

ConTenTs

november/december 2017 Volume XXIII/Issue 4

10

30

34

26 36

departmentS 04 editor’S report

featureS gary Seronik

A Thing of Beauty The August total eclipse was worth the wait . . . and more!

06 letterS 10 Sky newS briefS

paul deanS A Star Reveals Its Age; Mind the Gap; A Tale of Three (Stellar) Cities; A Blast in a Binary

22 Scoping tHe Sky ken Hewitt-wHite

Simple Sights in Cepheus The sparse open cluster NGC7380 benefits from glittery surroundings and wisps of nebulosity

24 Star cHart Night sky for late autumn for Canada and the northern United States

34 on tHe moon

gary Seronik

How Far the Moon?

A seemingly simple query has a surprisingly complex answer

41 conStellation corner ken Hewitt-wHite

Pisces Autumn’s night sky features a celestial sea populated with fish and several other interesting marine creatures

42 capturing tHe univerSe tony puerzer

Choosing a Lens for Astrophotography Is it possible to find camera optics that combine speed and quality with low cost?

46 coSmic muSingS terence dickinSon

Chasing the Big One

14 miSSion HigHligHtS by ivan Semeniuk

Cassini Bids Farewell To saTurn The most prolific planetary mission in the history of outer solar system exploration has left an enduring visual legacy

26 exploring tHe nigHt Sky by alan dyer

a Fine and FrosTy MeTeor shower A perfectly timed Geminid display, and the Moon covers Aldebaran—twice!

30 gallery

ECLIPSE

2017

SKYNEWS solar eClipse ConTesT Here’s a roundup of some of the finest reader photos of the August 21 eclipse

36 product review text and pHotograpHy by gary Seronik

orion’s MoTorized sTarBlasT TelesCope We test a scope that combines tracking with Dobsonian simplicity in a highly portable package

cover: this striking view of a crescent Saturn offers a perspective impossible from earth. the image was captured by the cassini spacecraft on July 18, 2009, when the probe was at a distance of approximately 2.1 million kilometres (1.3 million miles) from the ringed planet. the narrow, dark band seen on Saturn’s disc is the shadow cast by the planet’s rings.

COURTESY NASA/JPL-CALTECH/SSI

Some reflections on experiencing the August 21 total eclipse

viSit uS at

skynews.ca

EDITOR’S REPORT

by gary Seronik

a tHing of beauty The august total eclipse was worth the wait .. . and more!

T

haT was The MosT beautiful thing i’ve ever seen. as my precious 1 minute and 54 seconds of totality ended with a chromospheric burst of light, that thought flitted through my mind. But i’ve probably said something similar after every eclipse. it’s hard to compare one totality with another —memories eventually fade and are gradually corrupted by impressions accumulated after the fact. even so, this one really did feel special. That’s partly because it seemed to occupy a space in the distant future for such a very, very long time. anticipation has a way of making rare things seem more special.

My wife and i were able to secure a spot on the path of totality in central oregon, in The Cove palisades state park. But it took a lotterylike stroke of luck to do so. we’d scouted the area in the autumn of 2015, when we spent a couple of nights trying to figure out which specific Cove palisades campsite would be optimal for viewing the eclipse. a year later, in november 2016, i sat at my computer ready to click the “reserve” button on the oregon state park website, exactly one tick after midnight— the first moment reservations for the appropriate dates were available. (as it turns out, hundreds of other fanatics were also waiting.) Click . . . pause, and then nothing. every campsite was booked just like that. in disbelief (and, to be honest, with more than a little desperation), i kept hitting the “refresh” button on my web browser. after a few minutes, i was ready to admit defeat. i hit refresh one last time. To my utter astonishment, a couple of sites popped up as available. as fast as i could, i selected one of them (at this point, i was way past caring which site—any was better than none) and frantically entered my name and creditcard information into the on-line reservation form, deathly afraid my prize would be snatched away if i didn’t act quickly enough. when the confirmation number popped up 4

SKYNEWS

• NOVEMBER/DECEMBER 2017

WE HAVE CONTACT! this trio of images by gary Seronik shows, from left to right: second contact, mideclipse and third contact, as seen from the cove palisades State park, in oregon.

on my computer screen, i slumped in my chair, elated and exhausted. with accommodations nailed down, all that remained was to wait, prepare and anticipate. a few days before the big event, we loaded up our little travel trailer and drove south from our British Columbia home to The Cove palisades state park, situated a few kilometres southeast of the eclipse hotbed of Madras (a.k.a., “Madness”), oregon.

This was one of the regions Jay anderson highlighted in “waiting for the Big one,” which appeared in our July/august 2016 issue. a lot of people heeded Jay’s advice. our campground was, as expected, full. The oregon parks and recreation department had added more sites a few months earlier, and those quickly filled up too. every farmer on the path of totality seemed to be offering a plot of land for “self-contained camping,” often at sky-high prices. (one nearby location was charging $90 per night but didn’t seem to have many takers.)

To noneclipse people (in other words, the vast majority of the human race), all this probably seems like madness. one question i was asked over and over again by friends, neighbours and relatives (as i’m sure many readers were as well) was, why travel all that way? after all, the argument went, if i can see a 90 percent eclipse from home, why go through so much bother for an extra few

percent? i tried to explain the many important ways a partial event differs from totality, but i could tell i wasn’t getting through, even as they nodded in agreement. a 90 percent (or even 99 percent) partial isn’t like seeing 90 percent of a total eclipse. it’s as if the two phenomena need different names—referring to both as an “eclipse” badly undersells totality. if you’ve been there, you know. if you haven’t, you have to trust me that no photo (even the superb ones we present starting on page 30) or video can convey what the experience is really like. a partial eclipse—even a deep partial—doesn’t begin to hint at the shocking grandeur of totality. and that brings me back to my original impression. all the preparation, effort and expense were simply about trying to see the most beautiful thing ever. what’s that worth? For a die-hard eclipse fan, the answer is “a lot.” But everyone’s conception of beauty is different. Maybe it’s an eclipse that quickens your heart; perhaps a fine piece of music or artwork does the trick. in the same way an ardent art lover wouldn’t think it was nuts to fly to paris and queue up for hours at the louvre to spend a few moments taking in the Mona lisa, a dedicated eclipse chaser has no qualms about travelling to the ends of the earth to briefly stand in the Moon’s shadow. They’re two sides of the same beautiful coin. F

LETTERS

TAKING IN THE VIEW darren foltinek captured the scene above from his observing site at John day fossil beds national monument in oregon in a 1/13-second exposure at f/2.8 and iSo 400 taken with a canon eoS 6d camera and a 15mm fish-eye lens. left: foltinek enjoys the partial phase of the eclipse. PHOTO AT LEFT BY MARC LANGLOIS

total wonderment i, along with a pair of friends, joined hundreds of people from as far away as sweden to view totality at John day Fossil Beds national Monument, a remote and dry part of oregon that normally sees only a few visitors a week. on eclipse morning, we hiked up a ridge that provides expansive views across the rugged landscape and waited for the show to begin. The mood on the ridge was one of relaxed anticipation, but when the first black dimple of the lunar limb appeared against the solar disc, there was a sudden burst of excitement. This was it! Months of planning and two days of travel had brought us here— where the lunar shadow was destined to fall.

6

SKYNEWS

• NOVEMBER/DECEMBER 2017

over the next hour, the black lunar disc glided imperceptibly, with perfect symmetry, across the face of the sun. The light on the land grew soft and mellow, and the air became cool and still as the crescent sun slowly disappeared behind the Moon. suddenly, the sky to the west became very dark, as if a storm was approaching, but this time, the storm was the umbra of the lunar shadow, racing toward us at over 3,000 kilometres per hour. in an instant, the sun blinked out and was replaced by an impossibly black disc surrounded by bright white coronal streamers. at that moment, we experienced an overwhelming sensory shock as our environment transformed from an odd twilight with short vertical shadows into an utterly alien scene with a glowing black hole high in a dark sky. Totality was indescribably, eerily beautiful. all along the ridge, people erupted into shouts of wonder at this otherworldly spectacle. after two minutes that seemed to pass as quickly as two heartbeats, the sun exploded back into existence.

stunned, all i could think was, that really just happened!

Darren Foltinek Calgary, Alberta ediTor’s noTe: Readers can enjoy a full account of Foltinek’s eclipse adventure at his blog: frontrange.ca/blog.

a friendly eclipSe in caSper i really could not miss the august 21 eclipse, since it was occurring the day before my wedding anniversary. The timing presented an opportunity for my wife, Marusia, and i to celebrate a quarter-century together in memorable fashion. i filled the car with camera equipment, and we drove over 1,400 kilometres from our home in saskatchewan to our destination: Casper, wyoming. i’d wrestled with finding an eclipsewatching site in Casper. i was certain that most of the prime locations would be busy —even church parking lots were charging money for viewing spots! i decided on a

LETTERS

2 minutes and 26 seconds can pass until you watch an eclipse while trying to photograph it. as third contact arrived and daylight returned, the park erupted in jubilant cheers and celebration. everyone—most notably the many local residents who had never witnessed totality before—wanted to know when the next one would occur. i told them to get ready for april 8, 2024!

Don MacKinnon North Battleford, Saskatchewan

creating memorieS

SILVER ANNIVERSARY ECLIPSE the happy couple shortly after enjoying their fourth eclipse together, at verda James park in casper, wyoming. top: totality concluded with a spectacular diamond ring. PHOTOS BY DON MACKINNON

little park situated about a kilometre and a half north of the centre line, and as i pulled up on eclipse morning, i was delighted to see a group of observers with telescopes already set up. The park turned out to be the location selected by a group from the edmonton Centre/rasC. while getting ready, i had a chance to talk to many local people who had come out to enjoy the event. some arrived with picnic baskets and lawn chairs, and most had eclipse glasses. But it seemed that many of them knew very little about what was going to unfold. i fielded lots of questions and spent nearly five minutes during the partial phase persuading one gentleman that he would regret it for the rest of his life if he went home before totality. (he later thanked me!) i also got to talk with my fellow eclipse chasers from edmonton—it was great to run into a bunch of Canadians who, like me, had travelled a great distance to reach the centre line. you can never fully appreciate how fast

i’m sure SkyNews will receive many excellent eclipse photos shot by experienced astronomers using high-tech cameras and telescopes. none of my photos can compare to them. however, my humble pictures are far more meaningful to me because they are souvenirs of this awe-inspiring life experience. i observed the eclipse from evansville, a small town on the north bank of the north platte river, a few kilometres east of Casper, wyoming. one of my favourite photos shows the family of my friend hervé Cadene, who travelled all the way from France for the event. (They call themselves the “total eclipse pilgrims.”) hervé’s children are wearing their eclipse-viewing masks: César (the storm trooper), ysaline (the ninja turtle) and Cléophée (the cat). it’s these kinds of photos that i’ll cherish and share with friends—exactly the sort that nasa doesn’t take.

Julien Dompierre Montreal, Quebec MASKED TRIO whimsical eclipse-viewing masks are popping up more and more often. these were constructed by gluing creatively decorated paper plates to safe eclipse glasses.

PHOTO BY JULIEN DOMPIERRE

SkyNews volume xxiii, iSSue 4 editor gary Seronik editor@skynews.ca ken Hewitt-white alan dyer Janice mclean Susan dickinson paul deans, glenn ledrew, tony puerzer, ivan Semeniuk contributing astrophotographers klaus brasch, ron brecher, lynn Hilborn, malcolm park

associate editor contributing editor art director production manager contributors

publisher associate publisher advertising manager business manager customer Service

Æ khanscope

WATCH OUT FOR FALLING PRICES!AMATEURSEASRVTRINOGNOMER CHECK OUR SITE FOR DAILY

www.

Æ

skynews.ca Subscriptions one year $26, two years $42 (plus sales tax) u.S. addresses: one year uS$26; two years uS$42 international: uS$33 per year published six times a year by Skynews inc., 203–4920 dundas Street west, toronto, on m9a 1b7 printed in canada iSSn 0840-8939 publicationS mail agreement no. 40032351 return undeliverable canadian addreSSeS to circulation dept.

SKYNEWS, PO BOX 13, STN MAIN, DARTMOUTH, NS B2Y 3Y2

HOW TO GET IN TOUCH WITH SKYNEWS • To advertise: e-mail david webster at advertise@skynews.ca • To subscribe: the easiest way to subscribe to SkyNews is to call toll-free 1-866-759-0005 and order by credit card. it’s a free call from both canada and the united States. by mail, use the postage-paid subscription card bound into every issue. or visit skynews.ca/subscribe • To order a gift subscription: by credit card, use the toll-free line: 1-866-759-0005. by mail, use the postage-paid gift-subscription card bound into every issue.

• Change of address: call toll-free 1-866-759-0005, and have your old address label handy for reference. or visit skynews.ca/contact • Our mailing list: occasionally, we make our subscriber list available to carefully screened companies whose products and services may be of interest to our readers. if you prefer to have your name removed from this list and not receive these mailings, please write to us at the above address or call toll-free 1-866-759-0005.

• Problems with your subscription: call toll-free 1-866-759-0005, and have your address label handy for reference. or e-mail customer service: service@skynews.ca • Letters to the editor: we welcome letters, especially letters about your astronomy and stargazing experiences. e-mail: editor@skynews.ca • Submitting photographs: we welcome submissions of astronomical photos taken by our readers. digital images by e-mail should be sent in jpeg format to photo@skynews.ca • Submitting articles: please request our writers’ guidelines. mail: SkyNews, 203–4920 dundas Street west, toronto, on m9a 1b7 e-mail: editor@skynews.ca ©2017 SKYNEWS INC. all rights reserved. no part of this publication may be reproduced in any form without permission in writing from SkyNews.

BIG BANG

FOR YOUR BUCK!

CELESTRON NEXSTAR 8SE BUNDLE

Everything you need to get started in astronomy at a SPECIAL BUNDLE PRICE! • NexStar 8SE scope • 7amp power tank • Eyepiece and accessory kit • Dew protection shield

J. randy attwood colleen moloney david webster renata koziol 1-866-759-0005 service@skynews.ca

editor emeritus terence dickinson founding publisher canada Science and technology museum

DEALS

FEEL FREE TO COLLIMATE!

Æ

When was the last time you collimated your telescope?

Get this easy-to-use and well-made low-cost collimator today!

DE !

MA APAN J IN

S

FOR OVER

30 YEARS

.com

VIXEN 7x50 REGALO • Aluminum chassis • Bak-4 prisms • Antireflection multicoatings • Tripod mountable

Reg: $289 Sale price: $209!

Authorized MallinCam Dealer See the Universe Live and in Colour MEADE SERIES 6000 80mm f/6 ED TRIPLET APO REFRACTOR TELESCOPE (OTA ONLY)

TOP SELLER!

MEADE ETX125 OBSERVER

Æ

• Triplet 80mm objective lens • 480mm focal length • Fast focal ratio NEW of f/6 is ideal PRODUCT! for imaging or astrophotography • Extra-low dispersion (ED) FPL53 glass corrects chromatic aberration to improve colour rendition

127mm f/15 MAKSUTOVCASSEGRAIN GOTO TELESCOPE

The Super Eye for the Night Sky!

ALL MAJOR BRANDS: Losmandy • Daystar • Kite Optics • Meade • Celestron • Tele Vue • Kowa • Coronado

StellarVue • Novagrade • Sky-Watcher • Nikon • William Optics • Antares • Hotech • Farpoint • TeleGizmos • Baader iOptron • Telrad • Vixen Optics • MoonLite • Explore Scientific • MallinCam • Rigel • Lunt Solar Systems • ADM

SERVING BEGINNERS AND ADVANCED AMATEURS

WE SHIP CANADA WIDE | WE ACCEPT TRADE-INS WIDE SELECTION OF NEW AND USED EQUIPMENT

Æ

We service and repair most brands of telescopes and binoculars

ORDER ONLINE TODAY!

www.khanscope.com

1-800-580-7160 LOCAL: 416-783-4140

KHAN SCOPE CENTRE

OR CALL TOLL-FREE:

3243 Dufferin Street, Toronto, ON M6A 2T2 email: info@khanscope.com facebook.com/khanscope

HUNDREDS OF TELESCOPES IN STOCK!

SkyNews has gone digital!

Subscribe to our digital edition at

skynews.ca NOVEMBER/DECEMBER 2017 • SKYNEWS

9

SKY NEWS BRIEFS

by paul deanS

a Star revealS itS age

S

Tars—be they movie or celestial— don’t like to divulge how old they are.

For astronomers, it can be a challenge figuring out the age of the celestial variety. in February 2017, seven earth-sized worlds were discovered orbiting the cool, red dwarf star TrappisT-1. amazingly, three of the

really help constrain the evolution of the TrappisT-1 system, because the system has to have persisted for billions of years,” says adam Burgasser of the university of California, san diego. some of the clues used to estimate the age of TrappisT-1 include how fast the star is moving around the Milky way (speedier stars tend to be older), the chemical composition of its atmosphere and how many flares TrappisT-1 had during observational periods. These variables all point to a star substantially older than our sun—hence planets older than earth. what does this older age mean for the planets’ habitability? elderly stars flare less than younger stars, and TrappisT-1 is relatively quiet compared with other ultracool dwarfs. But since the planets are so close to the star, they have soaked up billions of years of high-energy radiation, which could have boiled off atmospheres and large amounts of water. “if there is life on these planets,” says Burgasser, “i would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years.”

planets reside in the star’s habitable zone (see SkyNews, May/June 2017, page 8). The dwarf was thought to be a mere 500 million years old.

But in a new study, researchers now think that the TrappisT-1 star is quite old: between 5.4 and 9.8 billion years. “our results

OLDER THAN OUR SOLAR SYSTEM? the trappiSt-1 system is viewed here from an imaginary vantage point on trappiSt-1f, the sixth most distant planet from the star. COURTESY NASA/JPL-CALTECH

S

oMe BoTanisTs collect flora, some zoologists gather fauna, and some astronomers amass extra-solar planets—exoplanets for short. like botanists and zoologists, astronomers try to categorize what they find. a recent attempt to do so revealed that the majority of exoplanets observed by the planet-hunting Kepler spacecraft fall into two distinct size groups. The first is rocky earth-like and super-earth planets, such as Kepler-452b, and the second is larger mini-neptunes, typified by Kepler-22b.

“This is a major new division in the family tree of planets,” says andrew howard of Caltech, “analogous to discovering that mammals and lizards are distinct branches on the tree of life.” howard’s team comprises colleagues from a variety of institutions, including lauren M. weiss of université de Montréal. using the Keck observatory, in hawaii, the researchers obtained spectral data on the stars hosting 2,000 Kepler planets and were able to measure the sizes of those planets with four times the precision of what had been achieved previously. The result: a striking gap between the groups of rocky earths and mini-neptunes.

The cause of the gap is not clear, but the Caltech group has two possible explanations. The first is the idea that nature makes plenty of planets roughly the size of earth. perhaps some of them acquired enough gas to “jump the gap” and become gaseous minineptunes. The second hypothesis relates to planets losing gas. if a planet acquires enough gas to place it in the gap, that gas could be burned off when exposed to radiation from the host star.

10

SKYNEWS

• NOVEMBER/DECEMBER 2017

notes Caltech’s erik petigura, a hubble Fellow: “we are currently working to understand what these mini-neptunes are made of, which should help explain why such planets form so easily around other stars and why they didn’t form around the sun.”

AN ODD GAP in this histogram, we see the number of planets per 100 stars as a function of planet size relative to earth. most planets discovered by kepler fall into two distinct size classes: (1) rocky earthlike and super-earth planets and (2) gaseous mini-neptunes.

COURTESY NASA/AMES/CALTECH/UNIVERSITY OF HAWAII (B. J. FULTON)

Small planetS come in two SizeS 12 Kepler-22b

number of planets per 100 Stars

mind tHe gap

10

Kepler-452b

8 6 4 2 0 1

1.5

2

3

4

6

Size relative to earth (radius)

8

12

ONE NEBULA, THREE STELLAR AGES different populations of young stars are marked in different colours. blue stars are the oldest, while red are the youngest. green stars are an intermediate age. COURTESY ESO/G. BECCARI

a tale of tHree (Stellar) citieS

W

hen you looK at the orion nebula, you’re peeking into a stellar nursery where star birth is currently under way. But is star formation a continuous process, or does it occur in bursts? using the omegaCaM wide-field camera attached to the european southern observatory’s VlT survey Telescope in Chile, a team led by astronomer Giacomo Beccari measured the luminosities and colours of all the stars in

the orion nebula Cluster—a 20-light-yeardiameter association of some 2,800 stars.

These observations allowed the astronomers to determine the masses and ages of the stars, which revealed a surprising result. “looking at the data for the first time was one of those ‘wow!’ moments that happen only once or twice in an astronomer’s lifetime,” says Beccari. “The incredible quality of the omegaCaM images

revealed, without any doubt, that we were seeing three distinct populations of stars in the central parts of orion.” adds Monika petr-Gotzens of the european southern observatory: “what we are witnessing is that the stars of a cluster at the beginning of their lives didn’t form altogether simultaneously. This may mean that our understanding of how stars form in clusters needs to be modified.” other measurements, such as the stars’ rotation speeds and spectra, likewise indicate that the stars must have different ages. indeed, the researchers found that the different stellar generations rotate at different speeds—the youngest stars are fastest; the oldest stars are slowest. The conclusion: These youthful suns in the orion nebula may have been born in three bursts of star formation during the past three million years.

All-Star Telesc pe www.All-StarTelescope.com FREE SHIPPING on most items *

*see website for details

1-866-310-8844 Didsbury, Alberta Sky-Watcher's Star Adventurer

ONLY FROM ALL-STAR!

Canada’s recipient of Celestron’s Perspectives on Imaging award

QHYCCD’s Polemaster

NOVEMBER/DECEMBER 2017 • SKYNEWS

11

a blaSt in a binary

W

hen a whiTe dwarF explodes, astronomers call it a Type ia supernova, but “to turn into a Type ia supernova, a white dwarf can’t be by itself,” explains dave sand of the university of arizona’s steward observatory. “it has to have some kind of companion.” That companion is either another white dwarf (the two objects spiral in toward each other and merge in a cataclysmic explosion) or a normal star from which the white dwarf steals material until it absorbs too much and explodes. The question is, which option is more likely? on the evening of March 10, 2017, supernova 2017cbv was caught by one of the robotic telescopes of the las Cumbres observatory (lCo). sand, who was on duty at the time, commanded other lCo scopes to immediately image the blast, which took place in the galaxy nGC5643, 55 million light-years away. The explosion was caught almost immediately, and the resulting ultraviolet light curve revealed a surprise: a short rise and fall in the supernova’s ultraviolet brightness during the first three to four days after the blast. “we think the bump in the light curve could be caused by material from the exploding white dwarf as it slams into the companion star,” says sand. The collision shocked the expanding supernova material and heated it to a blue glow heavy in ultraviolet light. such a shock could not have been produced if the companion had been another white dwarf and the pair collided. “we’ve been looking for this effect—a supernova crashing into

Sn 2017cbv

CAUGHT YOU! Sn 2017cbv lies in the outskirts of the spiral galaxy ngc5643. the supernova was captured thanks to a targeted observing campaign using the las cumbres observatory’s global network of 18 robotic telescopes. COURTESY B.J. FULTON/CALTECH

its companion star—since it was predicted in 2010,” adds Griffin hosseinzadeh of the university of California, santa Barbara. “hints have been seen before, but this time, the evidence is overwhelming.

The data are beautiful!” F

YOUR GATEWAY TO ASTRONOMY AND STARGAZING IN CANADA

skynews.ca

WE OFFER CANADA-WIDE SHIPPING!

Introducing a new standard in Light Pollution Filters SkyTech clip-in filters for Canon APC DSLRs Filters for Modified and Unmodified Cameras

As seen on Astrobackyard.com

Visit skynews.ca today!

Sign up and receive the free SkyNews e-newsletter every other Wednesday

Official Partner

ontariotelescope.com Where OTA means more. 905-487-6363 NOVEMBER/DECEMBER 2017 • SKYNEWS

13

Mission hiGhliGhTs

CASSINI BIDS FAREWELL TO e most prolific planetary mission in the history of outer solar system exploration has le an enduring visual legacy by ivan Semeniuk

14

SKYNEWS

• NOVEMBER/DECEMBER 2017

“W

hen we haVe aCTually seen that great arch swung over the equator of the planet without any visible connection, we cannot bring our minds to rest.” with those words, penned in 1859, scottish physicist James Clerk Maxwell set about demonstrating how the rings of saturn could be a collection of countless tiny moonlets moving around the plane, instead of a solid disc. Maxwell, who is best known for explaining the laws of electromagnetism, also managed to capture why astronomers have been mesmerized by saturn since the early days of the telescope.

To see the rings suspended in space around the solar system’s second largest planet is to be caught up in restless wonder. as one of the most accessible sights for beginning backyard astronomers, saturn seems to open the doorway to a universe of unexpected possibilities that beckons the willing explorer, no matter how experienced. and though it’s never closer than 1.2 billion kilometres, saturn has, nevertheless, proven to be uniquely tailored to inspire and delight the human eye when revealed up close.

For this reason, the Cassini mission was never going to be just another check mark on nasa’s to-do list. as the first spacecraft to conduct a detailed reconnaissance of saturn, its rings and many intriguing moons, Cassini has become our surrogate witness to what is arguably the most visually breathtaking place ever known.

Between its arrival at saturn in the summer of 2004 and its final moments in september 2017, Cassini generated enough data and discoveries to keep scientists engaged for a generation. But it has also taken us on a journey of a different kind—one in which beauty, drama and spectacle are all as fundamental to our experience of the cosmos as matter, gravity and light. F Ivan Semeniuk is a science reporter for The Globe and Mail newspaper and recipient of the 2016 Fleming Medal from the Royal Canadian Institute of Science.

16

SKYNEWS

• NOVEMBER/DECEMBER 2017

SHEER MAJESTY cassini trained its cameras across Saturn’s ring plane (opening photo) in april 2016 to obtain this spectacular mosaic of the planet one year before its northern summer solstice. this perspective shows the many divisions within the rings, where the gravitational influence of various Saturnian moons creates gaps among the trillions of bits of icy debris that make up the iconic feature. the widest and darkest of the gaps is the cassini division, also shown above, which was first noted in 1675 by giovanni cassini, the italian-french astronomer after whom the spacecraft is named. visible around Saturn’s north pole is the oddly geometrical cloud pattern known as the “hexagon.” launched in 1997, after 15 years of development and planning, the cassini mission has become one of the most successful in the history of planetary exploration. while many of its discoveries are specific to Saturn, cassini’s investigation of the complex dynamics at work within the planet’s rings has broader applications to the study of rings around other worlds and to planetforming discs surrounding distant stars.

OPENING PHOTO: COURTESY NASA/JPL-CALTECH/SSI ABOVE: COURTESY NASA/JPL/SSI

SHADOW PLAY within months of cassini’s arrival at Saturn, the mission’s imaging team began producing views that were not only stunningly beautiful but strikingly different from the way the planet had been seen before. in the above portrait, captured on november 7, 2004, Saturn’s northern hemisphere has a distinctly bluish tinge. cold temperatures during the northern winter produced a relatively cloud-free upper atmosphere that preferentially scattered blue light. the sand-coloured ring plane runs along the bottom of the image, with upwardslanting sunlight passing through the rings and casting a myriad of fine, curving shadows. Suspended against this backdrop is the icy moon mimas, which measures less than 400 kilometres across. in spite of its diminutive size, mimas contains about as much mass as the entire ring system. the bright streak near mimas is sunlight passing through the cassini division. COURTESY NASA/JPL-CALTECH/SSI TURBULENCE AT TOP Saturn’s north polar hurricane, right, appears as a rosy vortex in this false-colour close-up from november 2012. measuring 2,000 kilometres across and with clouds moving at 530 kilometres per hour, the storm was hidden in shadow for the first half of cassini’s exploration, emerging only as Saturn’s tilt gradually brought its northern hemisphere into sunlight. the redcoloured clouds closer to the centre of the vortex are at a lower elevation than the surrounding clouds that have a greenish tinge. this polar hurricane may be a long-lived phenomenon, though when the voyager 1 spacecraft imaged Saturn’s north pole in 1981, the probe wasn’t close enough to determine whether the feature was present. COURTESY NASA/JPL-CALTECH/SSI

NOVEMBER/DECEMBER 2017 • SKYNEWS

17

A TALE OF TWO GIANTS when cassini captured this view of Saturn and its largest moon, titan, in may 2012, right, both worlds were moving from spring equinox into northern summer. reduced sunlight on Saturn’s southern hemisphere gives the bottom half of the planet a dimmer, more bluish hue that is further enhanced by the dark shadows of the rings. titan, with its brownish orange haze made up of complex hydrocarbons, appears more uniform. even so, cassini was able to observe the effects of seasonal change in titan’s thick atmosphere and in the precipitation of liquid methane onto its icy surface. one of the signature achievements of the cassini mission was the detailed exploration of titan with radar mapping and infrared imaging. larger than the planet mercury, titan has proven to be an incredibly complex body that merits future exploration, perhaps with autonomous paddleboats that can ply its methane lakes. COURTESY NASA/JPL-CALTECH/SSI

18

SKYNEWS

• NOVEMBER/DECEMBER 2017

GREEN LANTERN this unusual perspective reveals Saturn as it is never seen from earth, with its rings backlit and the Sun hidden behind the planet. the greenish glow is a result of the colour enhancement of Saturn’s night, which is being illuminated by sunlight bouncing off the rings. the glow is brighter in the northern hemisphere because the rings were illuminated from above when this image was recorded in october 2012. the dark bands running through the green are not shadows of rings but the rings themselves revealed in silhouette. two of Saturn’s moons, enceladus and tethys, appear as starlike specks at lower left.

COURTESY NASA/JPL-CALTECH/SSI

A CRACKING GOOD VIEW cassini’s most astonishing and potentially far-reaching discovery was its sighting of mysterious jets of vapour emanating from cracks in Saturn’s small moon enceladus, below. after guiding the spacecraft through a succession of close encounters, mission scientists were able to determine that the jets are the gaseous emission from a saltwater ocean hidden beneath the moon’s icy crust. the crisscrossing crevices and the near-total absence of craters speak to a youthful surface that has been extensively reworked by tectonic activity— further evidence of a warm interior. the presence of liquid water on enceladus means that a “habitable zone” potentially exists in a region of the solar system located far from the Sun. cassini’s find has made enceladus a prime target in the search for life beyond earth and an enticing candidate for a followup mission to Saturn. COURTESY NASA/JPL/SSI

NOVEMBER/DECEMBER 2017 • SKYNEWS

19

SCOPING THE SKY

by ken Hewitt-wHite

Simple SigHtS in cepHeuS The sparse open cluster nGC7380 benefits from glittery surroundings and wisps of nebulosity

cepHeuS pair a pair b

d

pair c

ζ

ngc7380 ΟΣ480

pair d

1° telescope field of view

e

is C AM

ELO

PAR DA

CA

SS I

OP

EI

A

LACERTA

1

M3

Deneb

CEP

HE

US

ar

D oub le Cluste r

ED

• NOVEMBER/DECEMBER 2017

OM

SKYNEWS

DR

22

Better yet, it is located just 2⅓ degrees east of a famous variable star: Delta (d) Cephei. delta pulsates with the precision of a swiss watch. The archetype Cepheid variable, delta cycles between magnitude 3.5 and 4.4 every 5.36627 days. you can follow its constantly changing light output over several nights using binoculars—or even your bare eyes—by comparing delta’s brightness with 3.4-magnitude Zeta (ζ) Cephei and 4.2-magnitude Epsilon (e) Cephei, both lying only 2½ degrees westward. and something else: delta is a double star.

Known as struve 58 (Σ58), it sports a 6.1magnitude companion 41 arc seconds away —easy pickings for any telescope. nGC7380 hugs the eastern side of a narAN

D

eVoid oF Messier objects, Cepheus is often underappreciated by deep-sky observers. pity, because this midsized, medium bright star pattern is visible from Canadian latitudes all year round. This circumpolar aspect worked to my advantage one evening last July when i examined the open cluster NGC7380, in southeastern Cepheus. Back then, the target was already halfway up the northeastern sky. now, it’s almost directly overhead. astrophotographers enjoy nGC7380 as a two-part treasure. about 20 arc minutes across, the 7.2-magnitude cluster is a spritz of several dozen faint stars enveloped in a delicate nebulosity. For city-based visual observers, though, nGC7380 is simply a modest cluster minus the mist. Fortunately, nGC7380 is set in an attractive star field worthy of careful telescopic inspection.

Po l

CHARTS BY GLENN LEDREW

U

DETOUR FROM DELTA the famous variable star delta (d) cephei is located in the southeastern part of cepheus. you can monitor delta’s constantly changing magnitude by comparing it with neighbouring zeta (ζ), which is always brighter, and epsilon (e), which is usually dimmer. then aim your telescope a couple of degrees east of delta to locate ngc7380, with its fine field of double stars.

row, half-degree-tall isosceles triangle formed by three sixth- and seventh-magnitude stars. The tiny triangular asterism shows readily in my 7×50 binoculars, though there’s no sign of the associated cluster. My trusty 4¼inch f/6 newtonian reflector does better. when i place delta Cephei at the west edge of a 27× field of view, the triangle catches my eye near the east edge. i then centre the figure so that i can examine the adjacent cluster. admittedly, it isn’t a prize catch. at low power, i count, at most, a dozen cluster members, the brightest of which are 10th magnitude. at 72×, the count increases marginally to 14 suns—perhaps a few more. My 7.1-inch f/15 MaksutovCassegrain reflector at 90× adds a few more stars, bringing the total to 22.

The saving grace for this unremarkable Cepheus cluster is the aforementioned tri-

angular asterism next door. That triangle is loaded with double stars. its southeastern corner is marked by otto struve 480 (ΟΣ480), whose 7.6- and 8.6-magnitude elements, 31 arc seconds apart, make a fine duo in my smaller scope at 27×. The northern vertex is marked by what i’ll call Pair A. its 6.3- and 9.5-magnitude components are separated by 41 arc seconds. Just 3½ arc minutes farther north, Pair B (9.2, 10.9; 21 arc sec) resolves at 93×. That magnification also splits Pair C (9.6, 10.5; 35 arc sec) inside the triangle. in total, i get four doubles in a half-degree-long row. My Mak-Cass at 90× nails all four and adds Pair D (8.7, 11.7; 21 arc sec), which lies alongside the cluster, a bit east of ΟΣ480. however, the extremely faint attendant is barely visible in the Mak. if you observe under a country sky, you might try to detect the cluster’s surrounding nebulosity. For that challenge, you’ll

likely need a telescope of at least eight inches aperture, a low-power eyepiece with a wide field of view and an ultra high Contrast (uhC) filter. The uhC filter suppresses starlight that often competes with a nebula’s ghostly glow. i hunted for the nebulosity late last summer. Camped on a dark mountain, i scrutinized the area east of delta with my 18-inch f/4.5 dobsonian reflector. The big dob at 69× swept up three dozen (mostly very dim) pinpoints in nGC7380 and split the nearby double stars with ease. Finally, with the aid of a uhC filter and a dark-adapted eye, i noticed a pale, amorphous mist pervading the entire cluster. subtle and satisfying! F Living among the bright lights of Chilliwack, British Columbia, associate editor Ken Hewitt-White has learned to love cityfriendly star clusters of all shapes and sizes.

CLUSTER IN THE MIST doug nan Jiang’s image of open cluster ngc7380, complete with wreaths of nebulosity, was selected for a photo of the week at skynews.ca on march 3, 2017. ngc7380 is attended by five double stars, ranging from easy to difficult. Jiang captured this alluring scene during a 10-night span in September 2016 from Scarborough, ontario. He acquired a total of more than 20 hours of image data through S-ii, H-alpha and o-iii filters with a QHy814a camera and a takahashi fSQ-85ed apochromatic refractor telescope.

NOVEMBER/DECEMBER 2017 • SKYNEWS

23

STAR CHART FOR LATE AUTUMN

NE

OUR CHART SHOWS the major stars, planets and constellations visible from Canada and the northern united states within one

hour of these times: M LEO IN OR

early november: 11:30 p.m.; late november: 10:30 p.m. early december: 9:30 p.m.; late december: 8:30 p.m.

THE EDGE OF THE CHART represents the horizon; the overhead point is at centre. The faintest stars depicted shine at magnitude 5.0—a little brighter than what you can see under ideal conditions. on a moonless night in the country, you will see more stars than are shown here; deep in the city, you will see fewer. (The planets, when visible, are plotted for the middle of the date range covered by the chart.)

USING THE STAR CHART OUTDOORS: The chart is most effective when you use about one-quarter of it at a time,

NOV. 16 N waning crescent

moon 6° above venus-Jupiter pairing at dawn (see page 28) NOV. 17 leonid meteor

moon 4° above mars at dawn

meteor shower peaks under moonless skies (see page 29) DEC. 14 waning crescent

moon 3° above Jupiter at dawn

shower peaks under moonless skies

DEC. 18

new moon, 6:42 a.m., eSt

DEC. 21 Solstice (11:28 a.m.,

NOV. 18

NOV. 20 thin waxing crescent

moon 2° above Saturn and 7° above mercury at dusk

NOV. 22 N neptune station-

new moon, 1:30 a.m., eSt

eSt); winter officially begins in the northern hemisphere; Saturn in conjunction with the Sun first-quarter moon

ary 38 arc minutes below lambda (λ) aquarii

DEC. 26

NOV. 23 mercury at greatest

moon occults aldebaran (see page 29)

elongation (22°) east of the Sun

DEC. 30 waxing gibbous

N Impressive or relatively rare astronomical event

euse

DEC. 13/14 N geminid

Betelg

DEC. 13 waning crescent

moon 5° below mars in dawn sky

MARS can be sighted at dawn as a modest 1.7-magni-

tude reddish “star” in virgo. on nov. 29, it sits just 3° north-northeast of first-magnitude Spica. the waning crescent moon appears near mars on the mornings of nov. 15 and dec. 13.

JUPITER returns to the dawn sky in early november, shining

below mars and much brighter at magnitude –1.7. the two worlds approach each other throughout autumn and early winter as they head toward a tight conjunction in early January. on nov. 13, Jupiter is very close to venus (see page 28).

SKYNEWS

• NOVEMBER/DECEMBER 2017

LE

SATURN is in conjunction with the Sun on dec. 21, placing it out of

sight for most of november and december. you might catch Saturn with binoculars in early november low in the southwest during evening twilight. the planet will reappear in the morning sky in January.

URANUS is well placed for evening observing and is positioned due south at

11 p.m. (standard time) in early november and by 10 p.m. in early december. the 5.7-magnitude planet is found only 3° west of fourth-magnitude omicron (ο) piscium.

NEPTUNE is also ideally positioned for evening viewing. throughout november and

december, it glows at magnitude 7.9, just ½° below fourth-magnitude lambda (λ) aquarii. on nov. 22, neptune ceases its retrograde (westward) motion and gradually begins moving eastward.

For additional details or late-breaking information, visit our website (skynews.ca). Also consult the Observer’s Handbook, published by The Royal Astronomical Society of Canada (www.rasc.ca or 888-924-7272).

24

or

NOV. 15 waning crescent

last-quarter moon

OS

DEC. 10

autumn. it descends ever lower at dawn until middecember, when it will be too close to the Sun to be easily seen. on nov. 13, the brilliant planet passes only ¼° from Jupiter in bright morning twilight (see page 28).

OCER

¼° apart in morning twilight (see page 28)

I

VENUS ends its stint as a morning “star” this

4 a.m., eSt (357,492 km)

GEMIN

DEC. 4 moon at close perigee,

MON

NOV. 13 N venus and Jupiter

x

last-quarter moon

full moon, 10:47 a.m., eSt; largest full moon of 2017 (see page 28)

east of Spica in morning sky

Pol lu

NOV. 10

DEC. 3 N

elongations (22° east of the Sun) on nov. 23. However, the shallow angle of the ecliptic at dusk during this autumn-evening appearance keeps the planet close to the horizon. at the end of november, mercury passes south of Saturn, very low in the southwest during twilight.

CANIS MINOR

NOV. 5 N waning gibbous

NOV. 29 mars 3° north-north-

MERCURY reaches one of its frequent maximum

EAST

NOV. 26

moon occults aldebaran (see page 27); standard time begins (set clocks back 1 hour)

CER

first-quarter moon

NOV. 4

Procyon

tHe planetS

celeStial calendar full moon, 1:23 a.m., edt

C AN

which roughly equals a comfortable field of view in a given direction. outdoors, match the horizon compass direction on the chart with the actual direction you are facing. don’t be confused by the east and west points on the chart lying opposite their location on a map of earth. when the chart is held up to match the sky, with the direction you are facing at the bottom, the chart directions match the compass points. For best results when reading the chart outdoors, use a small flashlight heavily dimmed with red plastic or layers of brown paper. unfiltered lights greatly reduce night-vision sensitivity.

SE

NORTH ROTATING NIGHT SKY: During the night, the Earth’s rotation

on its axis slowly shifts the entire sky. This is the same motion that swings the Sun on its daily east-to-west trek. The rotational hub is Polaris, the North Star, located almost exactly above the Earth’s North Pole. Everything majestically marches counterclockwise around it, a motion that becomes evident after about half an hour.

H

ER C

UL

URSA R MAJO

ES

NW

Big D

DR A CO

R LY

A

Ve g

ipper

Little Dipper

a

URSA MINOR Polaris

LY N

PEIA ble Douster Clu

DELPHINUS

ER LAC

M31

Pl

EUS EQUUL

ULUM

PEGAS

S ei ad es

ARIES

eb

ON

Al d

ORI

G re a o f P t S q ua e g a re sus

EUS

U TAUR

US

ED A

WEST

CASSIO

PERS

OM

Altair

PEC VUL

E

TA

PH

DR

AQUILA

CE

ern r th N o C ro s s

ULA

IT TA SAG

De

ne

b

ALIS OPARD C AM E L

US

Ca p ella

AURIG A

TRIANG

GN CY

US

X

Ca s a ra

ES

IU DA N

US

S AU S I

SC PI t u

SCU

SOUTH

OR LPT

Fo

lh ma

a

I TR

NU

S

SW

ERI

CA

l

CETUS

PR

AQ UA R

ge

S

ICO

S

RN

US

n

PISC

Ri

PU

AN

CONSTELLATIONS:

The star groups linked by lines are the constellations created by our ancestors thousands of years ago as a way of mapping the night sky. Modern astronomers still use the traditional names, which give today’s stargazers a permanent link to the sky myths and legends of the past.

Cartography by Glenn LeDrew

NOVEMBER/DECEMBER 2017 • SKYNEWS

25

A FINE AND FROSTY METEOR SHOWER a perfectly timed Geminid display, and the Moon covers aldebaran—twice! by alan dyer

METEORS OVER THE VLA to create this geminid portrait, the author composited two dozen images taken over three hours on the peak night of the meteor shower in december 2015 at the very large array radio telescope in new mexico. PHOTO BY ALAN DYER

26

SKYNEWS

• NOVEMBER/DECEMBER 2017

explorinG The niGhT sKy

C

anadians tend to overlook the Geminid meteor shower. little wonder, given december’s typically chilly nights! But if you have clear skies, this prolific shower is worth getting bundled up for. we can also look forward to a pair of aldebaran occultations and a close conjunction involving the bright planets Jupiter and Venus.

DATE: SUNDAY, NOVEMBER 5 TYPE:

OCCULTATION VIEW:

TIME:

EVENING

TELESCOPE

ALDEBARAN OCCULTATION #1 throughout the year, the moon and aldebaran have met on a monthly basis, resulting in both occultations and conjunctions. as 2017 draws to a close, we will enjoy two more occultations. the first of these occurs on november 5, when the bright limb of the waning gibbous moon covers the 0.9-magnitude star in the early evening for observers in winnipeg, manitoba, and points east. for those farther west, aldebaran is eclipsed before the moon rises. but stargazers in Saskatchewan and alberta can see the star pop out from behind the dark lunar limb (a more dramatic sight than a bright-limb reappearance) shortly after moonrise. no matter where you’re located, the occultation is best observed with a small telescope at low magnification or even with tripod-mounted binoculars.

NOVEMBER 5 ALDEBARAN OCCULTATION City edmonton (mSt) winnipeg (cSt) toronto (eSt) montreal (eSt) Halifax (aSt)

Disappearance — 7:18 p.m.

8:05 p.m.

8:08 p.m.

9:09 p.m.

Reappearance 7:10 p.m.

8:05 p.m.

9:00 p.m.

9:05 p.m.

10:08 p.m.

note: The event occurs on the first evening after the conclusion of daylight time—be sure your clocks are set to standard time.

edmonton winnipeg toronto montreal Halifax

1° telescope field of view

CHART BY GLENN LEDREW

NOVEMBER/DECEMBER 2017 • SKYNEWS

27

explorinG The niGhT sKy DATE: MONDAY, NOVEMBER 13 TYPE:

CONJUNCTION

TIME:

DAWN

VIEW:

DATE: THURSDAY, NOVEMBER 16 TIME:

DAWN

CONJUNCTION

VIEW:

NAKED EYE

A DAWN TRIO

BINOCULARS

VENUS AND JUPITER: SO CLOSE BUT SO LOW! while venus slowly loses altitude as it nears the end of its reign as a morning “star,” Jupiter climbs higher at the beginning of a new apparition. on november 13, the two planets pass like ships in the night —or, rather, in the dawn. at roughly 6:30 a.m., local time, that morning, the bright twosome will stand side by side, venus on the left, Jupiter on the right, approximately 10 degrees above the east-southeast horizon and positioned 18 arc minutes (a little more than half a moon diameter) apart for observers across most of eastern and central canada. although venus beams at magnitude –3.9 and Jupiter shines at a respectable magnitude –1.7, you might need binoculars to catch them in bright morning twilight. by the time the tandem rises over the west coast, the separation will have increased to 23 arc minutes—still very close. perhaps the best instrument for viewing this unusually tight conjunction is a small telescope used at moderate magnification, which will allow you to see the discs of both worlds. venus will appear only 10 arc seconds wide, while Jupiter will be three times larger.

a lovely sight greets early risers on the morning of november 16, when a thin waning crescent moon shines just six degrees above Jupiter and venus. the planetary pair are now three degrees farther apart than during their close approach only 72 hours earlier. this conjunction will be particularly appealing for photographers looking to capture a striking dawn scene. with such an eye-catching trio, it’s easy to overlook the morning sky’s third planet, mars.

Shining at magnitude 1.7 and situated more than 20 degrees west of Jupiter, mars is full of promise as it slowly advances toward its closest opposition since 2003. but you’ll have to wait until July for that spectacle.

Mars moon, nov 15

nov 16

Jupiter Venus

ESE

DATE: SUNDAY, DECEMBER 3 TYPE:

SPECIAL FULL MOON

A PERIGEAN FULL MOON Venus

TYPE:

Jupiter

1° telescope field of view

as gary Seronik notes on page 34, the largest and closest full moon of 2017 occurs on december 3. expect the phrase “supermoon” to crop up frequently on-line and in television newscasts. the moon is full at 10:47 a.m., eSt, that day and reaches a perigee distance (the nearest point to earth in the moon’s orbit) of 357,492 kilometres the following day, at 4:00 a.m., eSt. So when the moon rises at sunset on december 3, it will be slightly past full and not yet at its closest.

SE

TIME:

EVENING VIEW:

NAKED EYE

occurring a little less than three weeks before winter solstice, the full moon sits in taurus near the same point on the ecliptic the Sun occupies shortly before the summer solstice. consequently, the full moon rises in the northeast and sets in the northwest— just as the Sun does in June. indeed, when the moon climbs to the meridian after midnight, the landscape might seem unusually brightly lit, especially if there’s snow on the ground. but the difference in illumination between a perigean full moon and any ALL CHARTS BY GLENN LEDREW

28

SKYNEWS

• NOVEMBER/DECEMBER 2017

× Radiant

lynx

orion betelgeuse

gemini

rigel

DATE: SATURDAY, DECEMBER 30

caniS minor monoceroS

TYPE:

procyon

cancer

OCCULTATION

VIEW:

EAST

NE

TIME:

EVENING

TELESCOPE

SE edmonton

DATE: DECEMBER 13/14 VIEW:

NAKED EYE

TYPE:

METEOR SHOWER

TIME:

EVENING

A GOOD YEAR FOR THE GEMINIDS unlike last year, the 2017 geminid meteor shower occurs with minimal interference from moonlight. the waning lunar crescent doesn’t rise until around 4 a.m., local time, on december 14, roughly two hours before the start of astronomical twilight. as it happens, the moon sits just a few degrees above Jupiter, offering a fine sight to cap off a night of meteor watching. but you needn’t make this an all-night session. the radiant point of the geminids rises in the northeast as twilight fades out on december 13. that means you can begin watching meteors as soon as it’s dark and continue for as long as you like while gemini climbs higher and higher and the rate of activity slowly increases. the geminids boast a rate of 120 meteors per hour—a theoretical number calculated for when the shower radiant is directly overhead and the display is viewed from a pristine, dark-sky location. in reality, observers usually witness less than the maximum. even so, that figure makes the geminids slightly more active than the better-known august perseids. of course, the difference in observing conditions (and comfort) between august and december is the main reason the perseids get more attention. but if you’re willing to brave the cold, this year’s display should be rewarding. the peak of the shower arrives in the early hours of december 14, at about 1 a.m., eSt, just before the radiant reaches its highest point. bundle up, lie back, and look up!

other full moon is too small to measure easily, even with a camera.

Skywatchers in western canada will be treated to a bonus aldebaran occultation at dawn on december 3, when the setting full moon passes in front of the star, low in the northwest. the event occurs at 6:56 a.m., mSt, for observers in edmonton, alberta, and at 6:06 a.m., pSt, over vancouver, british columbia.

RED SUPERMOON RISING SkyNews editor gary Seronik captured this view of the august 2014 perigean full moon rising over the atlantic ocean. the moon’s ruddy hue is due to atmospheric scattering— the same effect that produces red sunsets.

ALDEBARAN OCCULTATION #2

winnipeg toronto

the final aldebaran occulmontreal tation of the year occurs Halifax on the last Saturday of 2017. once again, eastern canada is favoured, but observers in eastern and northern alberta will see the star 1° telescope field of view disappear behind the dark limb of the waxing gibbous moon just after sunset. the disappearance might be a challenge to detect in bright twilight, but the sky will be much darker an hour later, when the star reappears from behind the bright lunar limb. viewing circumstances improve the farther east you are, where the moon is higher and the sky is darker as the occultation takes place. observers in ontario, Quebec and atlantic canada certainly should make a point of watching as the invisible, dark edge of the moon advances and causes the star’s light to wink out nearly instantly.

DECEMBER 30 ALDEBARAN OCCULTATION City edmonton (mSt) winnipeg (cSt) toronto (eSt) montreal (eSt) Halifax (aSt)

Disappearance 4:29 p.m. (sunset) 5:22 p.m. (twilight) 6:21 p.m.

6:28 p.m.

7:41 p.m.

Reappearance 5:18 p.m. (twilight) 6:19 p.m.

7:19 p.m.

7:27 p.m.

8:33 p.m.

Gallery WINNER we received several nicely done eclipse composites showing the sequence of events from beginning to end, but this entry from Quebec astrophotographer Jean guimond was our favourite. interestingly, of all the submissions featured in this gallery, his was the only one not shot with a dSlr camera. instead, guimond used a Sony cyber-shot dSc-rx10 iii “bridge” digital camera set to iSo 100 and working at f/5.6 with maximum zoom (a focal length equivalent to 600mm). it was fitted with a solar filter for the partial phases (removed for the diamond-ring shots and totality) and rode atop a vixen polarie tracking mount. He photographed the show from gallatin, tennessee, near nashville.

SKyNeWS Solar eclipSe conteSt here’s a roundup of some of the finest reader photos of the august 21 eclipse

The contest winner receives this Lunt LS50THa/ B400 50mm H-alpha solar telescope, courtesy of Lunt Solar Systems.

30

SKYNEWS

• NOVEMBER/DECEMBER 2017

W

e Knew ThaT The FirsT ToTal eClipse easily accessible to most Canadians since 1979 was going to be a big deal. we also knew that plenty of SkyNews readers would be travelling to the centre line and that many of them would be taking pictures. what we didn’t expect was the avalanche of submissions we received for our solar eclipse Contest. we asked for pictures, and we got ’em—by the hundreds. indeed, we received so many outstanding entries that it was nearly impossible to pick a mere handful to feature in these pages, let alone single out one as the prizewinner.

But with a publication deadline looming, our hand was forced, and we made our choices.

The images presented here really are the tip of the proverbial iceberg. it’s no exaggeration to say that we could easily publish another Gallery as good as this one stocked with a completely different set of eclipse portraits. so what sets one picture apart from another?

Basically, we looked for photos that not only were excellent on a technical level but also did a good job of conveying some of the many facets of this remarkable spectacle.

—Gary Seronik, Editor

É PUT A RING ON IT depending on your emotional disposition, the appearance of the “diamond ring” signalling the end of totality summons feelings of either joyous elation or great sadness. the brilliance of the solar photosphere is nicely captured in this image by gordon rife of Schomberg, ontario. while taking in the event from ravenna, nebraska, rife made the 1/4000-second exposure at iSo 100 with a canon eoS 60da dSlr camera on a Stellarvue 80mm refractor telescope fitted with a 0.8× tele vue reducer/flattener for an effective ratio of f/4.8. Ç BAILY’S ON THE ROCKS this sharply detailed shot of the eclipsed Sun by Scott mackenzie of vancouver, british columbia, shows the famed baily’s beads (sunlight peeking through valleys on the lunar limb) and the vivid rosy hues of the solar chromosphere, complete with distinctive prominences. mackenzie imaged the eclipse from grand ronde, oregon, with a canon eoS 60d dSlr camera and a takahashi fS-60Q telescope (600mm focal length, f/10).

NOVEMBER/DECEMBER 2017 • SKYNEWS

31

Å SEEING SPOTS although solar activity has been relatively low in recent months, a couple of attractive sunspot groups made their way onto the disc in time for the august eclipse. andreas gada of roseneath, ontario, recorded this view of the partial phase from near glendo, wyoming. gada used a canon eoS 5d mark iv dSlr camera and an astrophysics 130mm Starfire edf 5-inch refractor telescope equipped with a 2× teleconverter, for an effective focal length of 1,560mm. Ç ALL THAT GLITTERS our second eclipse sequence was created by wesley liikane of Severn bridge, ontario. liikane photographed the event from greenville, South carolina, using a canon eoS 7d mark ii dSlr camera with a Sigma 150-500mm zoom lens (set to 500mm and f/8) on a Sky-watcher Star adventurer portable tracking mount.

32

SKYNEWS

• NOVEMBER/DECEMBER 2017

MOONWALK to produce this kind of image requires not only an eclipse but also a friend willing to climb a mountain. luckily for photographer paul zizka of banff, alberta, he had both. zizka set up his camera (a canon eoS 5d mark iv dSlr fitted with a canon 100-400mm zoom lens and a 1.4× teleconverter) and photographed mike Stuart (the willing friend) scaling Ha ling peak in the rockies, located just west of canmore, alberta. “we communicated via radio,” says zizka, “and tried to line things up as best we could.”

Gallery É ALL TOGETHER NOW Here’s a familiar scene for many eclipse watchers. w. John mcdonald of victoria, british columbia, captured this wide-angle photo showing a group of observers (many from the victoria centre/raSc) enjoying the eclipse at monmouth, oregon. mcdonald used a tripod-mounted canon eoS 6d dSlr camera and a Sigma 15mm lens for this 1/15-second exposure at f/2.8 and iSo 640. Ç MY CORONA part of what makes each total eclipse unique (and so very beautiful) is the overall shape and many fine features of the solar corona. Jason orr travelled from guelph, ontario, to Hopkinsville, kentucky, to acquire the frames used for this corona study made with a pentax k-3 dSlr camera and a william optics 80mm refractor telescope. orr’s image shows the delicate streamers and polar plumes that distinguish the 2017 corona.

NOVEMBER/DECEMBER 2017 • SKYNEWS

33

ON THE MOON

by gary Seronik

How far tHe moon? a seemingly simple query has a surprisingly complex answer

A

s noTed on paGe 28, the largest full Moon of the year occurs on december 3, when our nearest celestial neighbour is at its closest for 2017. The Moon’s elliptical orbit around earth brings it as near as 356,500 kilometres at perigee and carries it as far as 406,700 kilometres at apogee. That’s a difference of more than 50,000 kilometres, which can make the lunar disc appear roughly seven percent bigger or smaller than average. The much discussed “supermoon” is a combination of our satellite being 100 percent illuminated around the time it’s at perigee. it’s one of those astronomical coincidences that people seem to enjoy and the popular press has taken notice of in recent years. with the december event, the Moon reaches its perigee distance of 357,492 kilometres roughly 17 hours after it’s precisely full—when it lies about 500 kilometres farther away. on an astronomical scale, that 500 kilometres amounts to splitting hairs.

But splitting hairs is what the supermoon concept is all about. Visually, it’s nearly impossible to notice that one full Moon is bigger than another, but the fact that it is makes the story interesting. so while we’re at it, let’s split a few more hairs. if you live in Toronto, for example, the Moon will be at a distance of about 357,795 kilometres from earth when it rises a little after 5 p.m. on december 3. But by the time it climbs to the meridian, at 12:45 a.m. (december 4), its distance will have shrunk by 6,071 kilometres! since, presumably, you don’t have a saturn V rocket parked in your backyard, you’re probably wondering how you can get so much closer to the Moon in just a few hours. Chalk it up to our home planet’s diurnal rotation.

The space between earth and the Moon is usually expressed as the geocentric distance; that is, from the centre of our planet to the centre of the Moon. But unless your name is otto lidenbrock, that’s not the

november 14, 2016, “supermoon”

34

SKYNEWS

• NOVEMBER/DECEMBER 2017

measure that matters most. Because we live on the surface of a 12,756-kilometre-diameter sphere, what we’re really after is the topocentric distance—and the difference between these two measures has some unexpected implications. For instance, if you watched the Moon rise from the earth’s equator (at a time of year when the lunar disc is near the celestial equator), our planet’s rotation would carry you 6,378 kilometres (the earth’s average radius) closer to the Moon by the time it shone directly overhead. in effect, that’s when you’d be positioned on top of our planet’s Moon-facing “bulge.” Twelve hours later, the earth’s rotation would have carried you twice that distance away, but you probably wouldn’t care, since the Moon would then LUNAR EXTREMES to illustrate the changing size of the lunar disc between perigee and apogee, both of the full moon images shown below were taken with the same equipment.

PHOTOS BY PATRICK WHELAN

June 7, 2017, “micromoon”

6,071 km

SHIFTING VANTAGE POINT thanks to the earth’s rotation, your personal distance from the moon can change by several thousand kilometres depending on whether the moon is near the horizon (rising or setting) or directly overhead. SKYNEWS ILLUSTRATION

GREAT GIFT IDEA!

be directly under your feet and out of sight.

The details of this closer/farther situation vary with latitude. if you draw a line at a right angle from the earth’s axis of rotation directly to its surface, you’ll find that the planet’s effective radius shrinks as you move from the equator to the poles.

From Vancouver, for example, the effective radius of earth is only 4,184 kilometres. and the farther north you go, the smaller that figure becomes. Moon gazers in yellowknife see their lunar distance vary by less than 3,000 kilometres.

But there’s an additional wrinkle: The Moon’s declination in the sky also plays an important role. The farther north the Moon is on the ecliptic, the more nearly overhead it is when it culminates for northern-hemisphere observers. so for Canadian Moon watchers, the few weeks around the winter solstice are the best time of year for this kind of hairsplitting—that’s when the full Moon reaches its most northerly position. leaving aside the effect of the earth’s rotation, you might wonder how we can

measure the Moon’s distance so accurately. we can thank the laws of physics and the efforts of apollo astronauts for that. The crews of apollo 11, 14 and 15 left retroreflector assemblies on the Moon (as did a few russian robotic explorers). These provide scientists on earth with a handy target at which they can aim powerful lasers. By measuring the time it takes for a laser beam to reach the lunar surface and return home, astronomers can gauge the Moon’s distance to an accuracy of about a millimetre. and what does that level of precision tell us? well, if you want to split a few more hairs, future supermoons will be slightly less super. Measurements reveal that our neighbouring world drifts about 38 millimetres farther away from earth every year. at this rate, in a few decades you’ll have to climb up a stepladder to see the Moon as big as it looks in 2017. Talk about splitting hairs! F Gary Seronik is a dedicated lunaphile and this magazine’s editor.

CELESTRON SKYMASTER DX 8×56 BINOCULARS If you’re looking for first-class astronomical binoculars, SkyNews editor emeritus Terence Dickinson recommends Celestron’s SkyMaster DX 8×56 binoculars, the best combination of quality optics and reasonable price available in this size.

FEATURES:

• 8x magnification porro prism binoculars

• fully multicoated optics for extremely sharp, clear views • rugged full-sized design for maximum image brightness

• nitrogen-purged for waterproof and fogproof performance

• multiposition twist-up eyecups for quick adjustment and optimum eye relief • Suitable for terrestrial or astronomical viewing • protective rubber covering for ultrafirm grip • large centre focus knob for easy focusing • carrying case included for travel and safe storage • limited lifetime warranty provides best protection and product support on the market

“in many ways,” he says, “the 8×56 is the ideal binocular for the backyard astronomer.” collecting 25 percent more light than standard 50mm binoculars and 96 percent more than 40mm binoculars, the 56mm is the largest binocular that is still comfortable to hand-hold. and the celestron Skymaster dx 8×56 is the lightest 56mm binocular we’ve tested.

FREE SHIPPING!

$269 plus applicable taxes.

Add the Celestron binocular tripod adapter for $30! this adapter allows you to mount your binoculars (porro or roof ) to a tripod for added stability and convenience. an absolute essential for stargazing! $299 plus applicable taxes.

1-888-924-7272, ext. 101 skynews.ca/binoculars canadian sales only. allow 3 to 6 weeks for delivery.

NOVEMBER/DECEMBER 2017 • SKYNEWS

35

produCT reView

orion’S motorized

STARBLAST we test a scope that combines tracking with dobsonian simplicity in a highly portable package

teleScope text and photography by gary Seronik

H

isToriCally, alTaziMuTh TelesCopes have had one big advantage and one big disadvantage compared with their equatorial brethren. pure simplicity is the main plus, as anyone who has used a dobsonian-style alt-az scope knows. such instruments move in easy-to-visualize up-and-down and side-to-side motions—just grab the scope and point it where you want to look. so what’s the disadvantage? an inability to automatically track a celestial target. or at least that was the main limitation until computerized mounts arrived on the scene. and that’s where a hybrid like the orion starBlast autoTracker fits in. it combines the ease of use of a dobsonian with the tracking capabilities normally associated with a more complex equatorial. in short, it potentially offers the best of both worlds. To find out whether it lives up to that potential, we arranged the loan of a test unit.

a different StarblaSt in a nutshell, the orion starBlast 114mm autoTracker is a 4½-inch f/4.4 reflector on a motorized altazimuth mount. included with the scope are a red-dot aiming device, a standard 1¼-inch rack-and-pinion focuser and a pair of eyepieces of 25mm and 10mm focal length, yielding magnifications of 20× and 50×. But the real story here—and the reason most readers will be considering this starBlast instead of the original model—is the mount. The autoTracker version includes motors and encoders in both the altitude and the azimuth axes, along with internal electronics that work together to keep objects centred in the telescope’s field of view. power is supplied by eight aa batteries (not included) or via an external 12-volt dC adapter (also not included).

Before using the autoTracker for the first time, you have to perform a setup procedure that involves matching an indicator on the altitude axis with your location’s latitude. unfortunately, this procedure isn’t described very clearly in the manual. The scale on the mount reads from 0 to 90 in both clockwise and counterclockwise directions. i was left scratching my head and wondering which “49” to use for setting my latitude. i guessed the one that positioned the scope pointing skyward, rather than toward the ground, and this ultimately proved correct. But, of course, with good instructions, the user wouldn’t have to guess in the first place!

36

SKYNEWS

• NOVEMBER/DECEMBER 2017

MOTORIZED MINI-DOB this 4½-inch reflector telescope from orion combines simple altazimuth motions and motorized tracking in an easy-to-use and highly portable package. the telescope can be aimed by using the directional arrow keys on the keypad, while slew speeds are selected by pushing one of the five numeric buttons.

get up and go once the computer brain of the starBlast knows your latitude, subsequent setups are straightforward. at the beginning of an observing session, simply level the mount, which is easy to do thanks to the built-in bubble level and a pair of adjustable feet on the “ground board.” next, aim the scope due north by sighting polaris, then turn on the power, and you’re good to go. you can find things by using the motor drive, controlled by a keypad permanently mounted on the top of the altitude strut, or by grabbing the tube and moving it manually, like a regular ol’ dobsonian. i found this latter approach best, since it was quick and helped conserve battery life. (Thankfully, the unit’s internal encoders prevent the mount from losing track of where it’s pointed.) For making fine position adjustments, though, the motorized slewing capability proved very useful. you can select speeds from 1 to 5, each with its

own direct-access button. i discovered that speeds 2 or 3 worked best for centring targets. The one caveat is that the drives in both axes on our sample starBlast had enough backlash that there was a delay of a second or two after pushing a directional button before the scope would respond. once acquired, targets stayed in the field of view indefinitely—certainly for as long as i’d spend looking at them. however, objects would be prone to drifting out of view if i failed to set up the scope initially with enough care. as useful as the motors are, i have to say that the mount worked well as a fully manual tabletop dobsonian. Friction in both axes is controlled by large hand knobs that make it easy to set just the right feel for smooth motion. This is a nice feature, since it ensures that the scope will remain usable should the batteries that power the motors die unexpectedly during an observing session.

OPTICS PLUS the Starblast’s optical train consists of a 114mm (4½-inch) primary mirror and a 34mm (1.35-inch) secondary. although the tilt of the secondary mirror can be tweaked, the main mirror is mounted in a nonadjustable cell. the 1¼-inch focuser and the red-dot aiming device can also be seen in the above image.

ALL IN THE BOX beginning stargazers will appreciate that the Starblast autotracker arrives as a complete package, including a red-dot finder and a pair of eyepieces. the optical tube assembly (ota) attaches to the mount via a vixen-style dovetail bracket.

overall, the autoTracker mount performed very well. and since the tube attaches via a common Vixen-style dovetail bracket, you can use the mount for a variety of telescopes, so long as you don’t exceed the 3.5kilogram recommended payload weight.

ota, eH? The starBlast 114mm optical tube assembly (oTa) features a three-vane spider supporting a 34mm (1.35-inch) diagonal mirror in an adjustable cell. however, the primary mirror is fixed in position and cannot be collimated. some will consider this a surprising choice (as i did), but this isn’t the first small reflector to go this route—the legendary edmund astroscan also has a nonadjustable primary. it’s curious, then, that a collimation cap is included and that the manual describes the primary mirror as having its centre marked “to achieve very precise collimation.” The mirror on our test scope did not have a centre

NOVEMBER/DECEMBER 2017 • SKYNEWS

37

mark, nor did another sample i saw. Beginners will likely be confused by this. The otherwise useful documentation fails to tell the user what to do if the primary does fall out of alignment—it insists that “no adjustments are necessary.”

Fortunately, the primary in our review sample was well aligned, so this was a nonissue.

The pair of included eyepieces are reasonable choices for a starter set. The 25mm yields a field of view slightly greater than 2½ degrees for locating and enjoying big deep-sky objects, while the 10mm offers enough magnification for scrutinizing finescale lunar features and modest planetary detail, including Jupiter’s two main cloud belts and saturn’s rings. in terms of performance, i was impressed with the 10mm ocular—it provided sharp images across the field of view. The 25mm, however, had trouble coping with the fast f/4.4 primary mirror and produced distorted star images only one-third of the way from the centre of the field. The ocular works well enough for finding objects, but an upgrade to a better one would be a priority if low-power viewing is something you enjoy.

The biggest complaint i have with the

TABLETOP OR TRIPOD CONVENIENCE a bubble level and adjustable feet, above, make it easy to set up the scope on a sturdy table. the large knob in the centre of the base is used to set the mount’s azimuth friction. most of the author’s testing was done with the Starblast mated to a bogen camera tripod, right, which allowed the eyepiece to be conveniently placed for seated viewing. the scope’s base includes a 3⁄ 8-16 socket to facilitate this arrangement.

scope is the quality of its primary mirror. it’s badly undercorrected, which means it produces views that are noticeably soft. This has to be kept in context, though. at low power, the performance of the scope is fine —it’s only when higher magnification is used, especially for the Moon and planets,

tracking and goto

I

won The sKy-waTCher Version of this instrument as a door prize at my local astronomy club and was delighted to discover it can work in full GoTo mode when equipped with a synscan hand controller. since my main telescope, an 8-inch sky-watcher collapsible dobsonian, came with just such a unit, i was able to instantly add GoTo capability to my new scope. i took this little sky-watcher to the 2017 Costa rica southern sky party. Mostly, i used it with a 13mm Tele Vue nagler eyepiece, which provided a magnification of 38× and a true field of two degrees. i found that if i took care with the initialization and set up using the two-star alignment procedure, the mount had no problem slewing from object to object and placing the target near the centre of the eyepiece field. as a BONUS FEATURE with the addition of a SynScan hand controller, the orion Starblast autotracker acquires full goto functionality. (the instrument pictured here is the Skywatcher version.)

38

SKYNEWS

• NOVEMBER/DECEMBER 2017

by dave cHapman

result, i was able to observe almost 100 deep-sky objects over five nights. occasionally, i bumped up to 83× with a 6mm Tele Vue radian eyepiece that yielded a true field of ¾ degree. at this magnification, the pointing accuracy was acceptable, though i often had to tweak the centring. however, by using the controller’s pointing accuracy enhancement feature, i was able to achieve improved GoTo performance in specific areas of the sky.

For me, adding the synscan hand unit made this the ultimate GoTo travelscope.

But i would quickly add that if you don’t already own the controller, its steep asking price (us$350) likely represents a significant deterrent. also, be aware that early versions of the synscan may not work with this telescope. if you decide to purchase a used hand unit, be sure to contact orion to confirm that it’ll work with your scope. F Dave Chapman is editor emeritus of The Royal Astronomical Society of Canada’s observer’s handbook.

NOW OPEN FOR SUBMISSIONS that images lack the sharpness better optics would provide. i’d give the primary mirror a letter grade of C—adequate, but with plenty of room for improvement.

in tHe field i used the starBlast autoTracker over many nights last summer, including at the Mount Kobau star party in British Columbia. i usually affixed the scope to my Bogen camera tripod via the 3⁄8-16 socket found on the base of the mount. This arrangement proved to be stable and highly portable. i really had fun (dare i say, had a “blast?”) using the starBlast to sweep up clusters and nebulas in the Milky way. it was a treat taking in the sights without having to continually nudge the scope to keep them in view, especially when using the 10mm eyepiece. i also found the scope to be an ideal companion for a night of imaging. i could centre an object in the eyepiece, leave it for a while to attend to my astrophotography equipment, then continue viewing without having to refind my target. But, mostly, i used it casually for poking around the sky or for quick looks at the Moon. as a grab-and-go instrument, the starBlast autoTracker has many virtues. i think beginners will appreciate it the most. This entry-level orion is lightweight and simple to set up, and it provides wide-field views that should ensure plenty of enjoyable nights under the stars. F Gary Seronik is this magazine’s editor and an experienced telescope maker and equipment reviewer.

16th Annual

SkyNews

PHOTO of the WEEK CO N T E S T Send us your best photos, and you could win in one of the categories below or be chosen as the overall Grand Prize winner.

Enter today...and every week!

See page 41 for more details.

GRAND PRIZE Advanced VX 8-inch EdgeHD Schmidt-Cassegrain telescope

celestron.com

CATEGORY: Best Deep-Sky Image Prize: MallinCam UNIVERSE colour CCD camera

CATEGORY: Best Lunar, Planetary or Solar Photo Prize: StarNavigator NG 125mm Maksutov telescope, mount and tripod

ORION STARBLAST 114MM AUTOTRACKER TELESCOPE Approximate retail price: US$280 Available from Orion dealers across Canada or directly from Orion Telescopes & Binoculars www.telescope.com Summary: a nifty auto-tracking minidobsonian that’s easy to set up and use.

PLUSES • mount tracks accurately • good set of included accessories • Highly portable PROBLEMS • primary mirror mediocre • power needed for tracking function • Sturdy table or tripod required

meade.com

CATEGORY: Best Tripod-Mounted or Tracker Photo Prize: Sky-Watcher Star Adventurer Astro Bundle

mallincam.com

CATEGORY: Readers’ Choice Award Prize: iOptron SkyGuider Pro camera mount

ca.skywatcher.com

Telescope and tripod not included.

ioptron.com

view new Photos of the Week at

SkyNews.ca

16th year of amazing reader photos

STAR C

H

ND O A R TS A

B S E RV

S FO ING TIP

FALL R LATE BER/D NOVEM

y& stronom A f o e n Magazi

nadian The Ca

R 2017 ECEMBE

ing Stargaz

LL TO E W E FAR

N R U SAT ges from lar ima reaking u c ta c e db Sp s groun Cassini’ mission r 13-yea

SUBSCRIBE TO WIN a highly portable Meade 40mm Personal Solar Telescope with case—the world’s most popular telescope to observe the Sun. A $1,099 retail value.

CLIPSE photos !

OTAsLaEnd sensational T 7 1 iss them 0 2 er report Don’t m : S d R a e O R E ID MET GEMIN Y PHOTOS SK NIGHTg the right lens Choosin

W zed StarB REVIE ri ’s moto Orion

1

S SKYNEW

•

EMBER ER/DEC NOVEMB

pe last sco AN SATURN

D ITS

CE MAGNIFI

NT RIN

E/DINI

BY CA ERSS ED MB AGVE GS AS IMNO

| $5.99 nuary 15 40 until Ja Display 03 23 51 R0 96 PM 40

visit sk

ynews.

ca

2017

SkyGift

Give SkyNews this holiday season, and your friends and relatives will never miss an important celestial event again—

like seeing Mars in July 2018 at its closest and brightest in 15 years!

Order your gift subscriptions today!

Simply complete the card opposite, call toll-free 1-866-SKY-0005 (1-866-759-0005) or visit us at skynews.ca/gift2017

CONSTELLATION CORNER

by ken Hewitt-wHite

SkyNews 16th Annual PHOTO of the WEEK

piSceS autumn’s night sky features a celestial sea populated with fish and several other interesting marine creatures

CO N T E S T HOW TO ENTER go to skynews.ca/contest-rules for contest rules, detailed instructions for submitting your photos and other information. to be eligible to win, submissions must be received by June 1, 2018. you may enter as often as you wish, but please don’t send more than 10 of your best photos per entry.

THIS CONTEST IS OPEN TO RESIDENTS OF CANADA ONLY.

THREE EASY STEPS Step 1.

Send your best astrophotos via e-mail to photo@skynews.ca.

O

n Canada’s west Coast, late autumn means almost endless rain. on the rare occasions when the overcast dissipates after dark, we find the large, dim constellation pisces in a drab sector of the zodiac below pegasus and andromeda. stargazers of the ancient Middle east experienced their rainy season when the sun passed through pisces every spring. over time, a broad swath of sky surrounding pisces became known as “the waters.”

This astral aquarium is home to a whale, a dolphin, a sea goat (whatever that is!), a water carrier and, of course, several fish. old star charts show the twin fish of pisces connected by a lengthy, twisted ribbon sharply bent roughly halfway along. in the sky, the slender fabric is represented by a sprawling V-shaped star pattern. The ribbon is knotted at the bottom of the “V” by 3.8-magnitude alpha (α) piscium. The arabic name for this star is alrescha, which means “cord.”

The most easily recognizable—indeed, famous—part of pisces is a seven-degreewide elliptical asterism called the Circlet, which symbolizes one of the two celestial fishes. Faint though subtly alluring, the Circlet is outlined principally by five fourth-

and fifth-magnitude stars called Theta (θ), Gamma (γ), Kappa (κ), lambda (λ) and iota (ι) piscium. Bolstering that quintet is similarly bright 7 piscium (between Theta and Gamma), plus a slowly changing reddish-hued variable star called Tx piscium (between lambda and iota). we might think of the fish as dangling from a fishing line, but classical writers insisted otherwise. roman lore identified pisces as the goddess Venus and her son Cupid. desperate to escape the monster Typhon, Venus and Cupid jumped into the sea and were transformed into (or were carried away by) a pair of fish. so that they wouldn’t become separated from each other, mother and son connected themselves with an umbilical cord.

Few modern-day urban dwellers notice pisces’ pale pattern, but more than 2,000 years ago, this constellation was well known and enjoyed a notoriety of biblical proportions. in 7 B.C., it was the backdrop for a rare celestial drama: Jupiter (star of david) and saturn (protector of israel) acted out a yearlong, back-and-forth triple conjunction within pisces. This confluence of bright planets is one of several explanations offered for the star of Bethlehem. F

Step 2. we’ll select the best submissions and publish a new photo every week at skynews.ca. the images posted on-line are eligible for our readers’ choice award.

Step 3. the year’s finest photos and honourable mentions will be published in the Sept./oct. 2018 issue of SkyNews.

RULES AND INSTRUCTIONS there are no entry fees or entry forms.

SEE PAGE 39 FOR PRIZE DESCRIPTIONS. photos previously submitted to the photo of the week gallery, including those not published, are automatically eligible. do not resubmit photos already sent. images should be in Jpeg format, 2,400 pixels wide, and should not have text (such as labels, copyright notices or other information) imprinted on them. composite images (for example, those with foregrounds added digitally) are not eligible; however, photos consisting of stitched mosaics and panoramas are allowed. please include as many of the following details as possible: camera make, lens, focal ratio, exposure time, processing steps, location and date. put your name, phone number and address in your e-mail.

SkyNews.ca

IMAGE FROM ALEXANDER JAMIESON’S 1822 CELESTIAL ATLAS

NOVEMBER/DECEMBER 2017 • SKYNEWS

41

CAPTURING THE UNIVERSE

text and photography by tony puerzer

cHooSing a lenS for aStropHotograpHy is it possible to find camera optics that combine speed and quality with low cost?

S

peed, qualiTy, priCe: pick two. you’ve probably heard some version of the above phrase if you’ve ever hired a contractor or had a mechanic work on your car. Basically, it’s a variation of the familiar adage “you can’t have it all.” and yet when it comes to selecting lenses for astrophotography, you really can have it all—but only if you choose carefully.

balancing factorS in astrophotography, optical speed is the single most important factor. a “fast” lens is one with a low f-stop number, which is simply the ratio between its focal length and 42

SKYNEWS

• NOVEMBER/DECEMBER 2017

WIDER THAN WIDE a fish-eye lens affords the widest possible view of the night sky, capturing the dramatic sweep of the milky way. the canon 15mm fish-eye used for this photo offers a 180degree diagonal field of view when mounted on a full-frame camera, such as the canon 6d. the camera was set to iSo 3200 with the lens wide open at f/2.8. an ioptron Skytracker mount was used to prevent the stars from trailing during the 2-minute exposure.

aperture. For example, a 28mm lens with an aperture of 10mm would be an f/2.8 optic. your digital camera probably came with an inexpensive “kit” zoom lens with an f-ratio that varies from f/3.5 to f/5.6. That’s fine for general use, but if you’re looking to up your astrophoto game, you’ll need to consider a lens with an opening of f/2.8 or larger.

The lower the f-stop number, the shorter the exposure you’ll need to record dim

objects. Keeping exposure times short is essential if you want to use a fixed tripod and avoid star trails. But such a lens has important benefits even when your camera is mounted on a tracking platform or an equatorial mount. Generally, the longer the exposure, the more likely you’re going to get pictures that show errors from imprecise polar alignment or slop in the mount’s gears and motors. and since digital cam-

100% CROP

EXPENSIVE MEDIOCRITY price is not always a good indicator of optical quality. the author’s canon 16-35mm f/2.8 lens (mark i version, which cost over $2,000) offers a wonderful field of view and is great for architectural and landscape photography, but it suffers from horrendous coma at the edges of the frame (inset), making it marginal for astrophotography on a full-frame camera such as the canon 6d used here.

eras are fairly insensitive to the deep red part of the spectrum, where so much of the light from emission nebulas resides, a fast lens helps deliver as many photons as possible to the camera’s detector. of course, there’s no point in buying any lens with image quality so poor that the results are always disappointing. no lens is perfect, but some aberrations are less of a problem than others. with just a click of the mouse, image-editing software, such as adobe lightroom or photoshop, can correct for vignetting, barrel and pincushion distortion and even mild chromatic aberration. as long as a lens doesn’t exhibit severe coma (where stars are stretched into cometlike streaks at the edges of the frame) or field curvature (which prevents the entire image from coming to focus at once), it’ll perform reasonably well for shooting the night sky. if your lens does show these kinds of aberrations, try stopping it down from wide open. you’ll get improved star images but at the expense of longer exposures. unfortunately, good, fast lenses aren’t

cheap. To avoid breaking the bank, you’ll need to choose the features that matter most for astrophotography. auto-focus, image stabilization and auto-aperture are all great for daytime photography, but you'll end up turning them off when photographing the stars. you can save money by choosing a lens without these features. in addition, significant cost savings can be had by avoiding zoom lenses in favour of “prime” lenses that have a single fixed focal length. Fast zooms are among the priciest lenses on the market! if you’re willing to keep things basic, you’ll discover there’s a wide selection of excellent models at a reasonable cost.

focal-lengtH cHoiceS The ideal focal length for astrophotography depends entirely on what you want to image. a constellation portrait requires a much different setup than a close-up of a globular cluster. But if you’re purchasing your first astrophotography lens, i recommend choosing an ultrawide unit. with lenses in the 8-to-16mm range, you can capture big swaths of the night sky, such as the majestic arch of the Milky way, while still including some of the foreground landscape for added visual interest. These focal lengths also allow you to make long exposures without a tracking mount before NOVEMBER/DECEMBER 2017 • SKYNEWS

43

FAMILY PORTRAIT a couple of the author’s favourite lenses for wide-field astrophotography are shown here: the canon 15mm f/2.8 fish-eye, at left, and the 10-22mm wide-angle zoom, centre. another favourite is the 50mm f/1.4 mounted on his astro-modified canon eoS 60d camera, right.

star trailing becomes apparent. Brands such as samyang and rokinon offer a number of relatively inexpensive ultrawide prime lenses that fit a variety of popular cameras. although fish-eye lenses are highly specialized, don’t rule them out. one of my favourites is a discontinued Canon 15mm model that i picked up used for a good price. admittedly, it suffers from some pretty severe coma at the edges of the field, but that’s a defect i’m willing to live with to achieve an all-encompassing perspective.

if your budget permits additional purchases, i’d opt for a wide-angle lens in the 16-to-28mm range. These slightly longer focal lengths still allow you to include some of the horizon as well as large areas of the night sky—especially when shooting in “portrait” orientation. note, however, that while these focal lengths can yield untrailed stars when used on a fixed tripod, longer exposures will require a tracking platform or an equatorial mount.

Keep in mind that if your camera has

an aps-C-sized sensor, you’ll need to do a little math to find lenses that match the ones i recommend. simply divide the focal length you want by the crop factor of your camera. The 1.6× crop factor of the sensor in my Canon 60d, for example, means that a 10mm lens will cover the same field of view that a 16mm model provides on my full-frame Canon 6d. For cropped nikon dslrs, the conversion factor is 1.5×. obviously, longer-focal-length lenses are extremely useful for imaging specific deepsky objects, but the options described here are the best place to begin. i’ll tackle the subject of normal and telephoto lenses in an upcoming column. in the meantime, get shooting with a wide-angle lens. if you have the itch to experiment, try the lens that came with your camera as well. when it comes to speed, quality and price, a so-called kit lens may not be particularly fast or an optical champ, but a lens you already have costs nothing—and one out of three ain’t bad! F Tony Puerzer is a full-time professional photographer and part-time amateur astronomer living in Nanaimo, British Columbia.

Order the Best for 2018 U.S. or n Canadia! n io edit

Observer’s Handbook Observer’s Calendar The must-have resource for astronomers, Your guide to daily astronomical events. now available as a U.S. edition. $28.95* $17.95* The Royal Astronomical Society of Canada—29 local Centres from coast to coast.

For more information and to learn about membership, call toll-free 1-888-924-7272; email mempub@rasc.ca; or visit us online. *Plus S&H and applicable taxes.

(May be available through your local Centre.)

44

SKYNEWS

• NOVEMBER/DECEMBER 2017

rasc.ca

Reach 50,000 amateur astronomers in Canada!

aStromart

Call 416-832-9732 to place your advertisement today

New Products:

12V Powered 7-Port USB 3.0 “Charging” Hub 25 Amp AC-DC Power Supply DigiFire 8 and 12 Dew Controllers Power Supply and Cord Management AND, of course, the wŽƌůĚ͛Ɛ ĮŶĞst dew heaters Our new dew controllers can power your DSLR and other 12V devices too!

800-393-5456

in V P is O ick it u nt e s ar rin io g ! ,

www.kendrickastro.com

SEE FOR YOURSELF

PORTAL ARIZONA SKY SHARE LLC

Fractional Ownership Option $39,000—Available Now

FREE SHIPPING (some conditions apply)

Durham Skies Astronomy & Birding

Telescopes ´ Binoculars ´ Spotting Scopes Astro-imaging ´ Digiscoping Birding & Star Guides ´ In-class Seminars

“Service and Inspiration for All Enthusiasts!”

Gary Wilkins gary@durhamskies.com

durhamskies.com Check out our showroom next to the Pickering GO Station (on Bayly Street east of Liverpool Road)

1410 Bayly Street, Pickering, Ontario Toll-free: 1-855-LOOK-N-UP (1-855-566-5687)

l Canadian Lighting Company ECOLIGHTS Í No disruptive blue light Í Fully shielded Í No light trespass Í Auto controller and dimmer

1-800-278-2032

$

269

ONLY TWO SPOTS LEFT!

THE PROPERTY: • Arizona Sky Village near Portal, Arizona • Two lots on 8 acres • 1,664 square feet, fully furnished, 3-bedroom, 2-bath • 10' x 20' observing pad with power and internet THE CONCEPT: • Privately owned LLC with five partners at 20% share • 8-12 weeks per year • Expenses and property investments shared • Three owners committed, only two opportunities remain!

For more information, please contact:

portalarizonaskyshare@gmail.com

SOURCE EQUIPMENT

YOUR

FOR

ASTRONOMY IN MANITOBA

We carry Meade, Sky-Watcher, William Optics, Telerad and more!

plus taxes, shipping and handling

CLC EcoLights A division of CSbG

EcoLights.ca

#4-1329 Niakwa Rd. East Winnipeg, Manitoba R2J 3T4

204-253-7499 • sideline@mts.net

Celestron TeleVue Takahashi Swarovski Sky-Watcher Zeiss Meade Nikon ExploreScientific Losmandy Vortex and more Celestron Evolution Telescopes

www.focusscientific.com 911 Carling Ave., Ottawa, ON K1Y 4E3 Local Phone: 613-723-1350 Toll-free: 1-877-815-1350 sales@focusscientific.com

SKYNEWS CLASSIFIED BUY & SELL TELESCOPE EQUIPMENT AND ACCESSORIES on Canada’s premier astro-classified website. new ads daily. place your free ad at:

www.astrobuysell.com

NOVEMBER/DECEMBER 2017 • SKYNEWS

45

COSMIC MUSINGS

by terence dickinSon

cHaSing tHe big one some reflections on experiencing the august 21 total eclipse

L

iKe Many SkyNews readers, i’d planned for years to travel south of the border to observe last august’s historic north america-wide total eclipse of the sun. after five previous trips to stand in the Moon’s shadow, i’d learned the importance of travelling light, staying mobile and being prepared. i knew that if clouds were to interfere and a quick escape to a clearer sky became necessary, having detailed maps of the area is the key—preferably with someone other than the driver doing the navigating!

The goal was to spend totality at my group’s chosen site in central nebraska enjoying the spectacle of the eclipse, rather than dodging clouds and repacking equipment at the last minute. But when high clouds drifted over our campsite an hour before totality, i—along with three of my fellow eclipse chasers—took to the road.

Fortunately, nebraska is mostly flat and, therefore, ideal for this kind of manoeuvring. our map showed plenty of options

along lightly travelled gravel roads between vast fields of seven-foot-high corn. within 40 minutes, we’d driven out from under the clouds to a completely clear, deep blue sky. now it was time to set up. Thanks to my “travel light” regime, i didn’t have much preparation to do. i simply had to unfold my reclining lawn chair (rented at an rV outlet) and dig out my binoculars. Binos, of course, are highly portable, and i’ve found them to be the optimum visual aid for viewing totality. in particular, i’d noticed many image-stabilized binoculars in evidence that day—the Canon 10×30 and 12×36 models appeared to be the choice of the eclipse cognoscenti. i’m a huge fan of image-stabilized binoculars too. so enamoured am i with the performance of these glasses that i own three different models. i had two with me that day: 12×36 and 18×50 Canons. when the moment of totality arrived and filterless observing became possi ble, the binocular view was magnificent. instantly, the binos revealed three pink prominences arranged like frozen fingers

of fire clawing at the sun’s circumference.

The bright inner corona surrounding the blackened solar disc gave the scene an awesome hole-in-the-sky appearance. as totality progressed, the Moon shifted eastward to “eclipse” one solar prominence, then expose another. our allotted 150 seconds of totality flashed by in no time as i seemed to float, suspended on my canvas lawn chair.

Then, with a swiftly intensifying diamond ring, it was over. was it worth the trip? emphatically, yes. when will we get to witness all this again from north america? readers of the september/october issue already know the answer. on april 8, 2024, the Moon’s shadow crosses the continent once more, starting in Mexico, then sweeping northeastward through the united states and parts of Canada. it turns out that totality will be visible from. . . my backyard!! F Editor emeritus Terence Dickinson lives a short drive north of Kingston, Ontario.

NEBRASKA PROMINENCES toronto, ontario, eclipse photographer michael watson captured this detailed view of the august 21 event from a location off state highway 71, 42 kilometres north of Scottsbluff, nebraska.

46

SKYNEWS

• NOVEMBER/DECEMBER 2017