The Southern Astronomer - July & August 2017 by Brian Halls

The Southern Astronomer No.106 â&#x20AC;&#x201C; July-August 2017

SOUTHERN ASTRONOMER THE

MONTHLY MAGAZINE OF WORTHING ASTRONOMERS & WORTHING SKYWATCHERS

The Southern Astronomer No.106 – July/August 2017

WORTHING ASTRONOMERS No fees, no Committee; just enjoying the night sky together.

ormed in 2008 by a group of regular and practical observers, Worthing Astronomers is a free to join society now with a membership of over 450 persons, who have a common interest in Astronomy and its associated subjects – no internal politics, no fees, no committees, just astronomy!

The Southern Astronomer This Issue Astronomy This Month; Observing Eclipses The Planets in July and August Workshop Report: Solar Eclipses Observing Meteors & Comets Observing the Sun: Report The Night Sky in July & August

Our aim is simple – to bring astronomy to the public in general and to help and assist our membership in observing the night sky. With the aid of this newsletter, website, social media, regular star parties, workshops and public observing events we hope to encourage and share our interests in observing the sky with the public, our colleagues in our own group and with those of neighbouring astronomical societies.

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Cover & Comment

We try and meet at least once a month (when weather conditions allow) to do some observing but at the moment we do hold, every two months, a Workshop evening when we get a chance to meet up, exchange ideas and tips and help each other to make the most of observing the sky above us. Occasionally a guest speaker will talk about an aspect of practical, hands on astronomical observing.

The cover picture is by local amateur astronomer and eclipse chaser, Nick Quinn and shows the ‘face of the man-in-the-moon’ at a total solar eclipse – hence the over exposed coronal areas around the Moon. You will notice a change in this issue of the newsletter – this issue covers two months. The next issue will be out at the end of August and will cover the months of September and October.

These Workshop evenings are usually held on the first Friday of every other month (February, April, June, August, October and, December) at Goring Methodist Church Hall, Bury Drive (off of Aldsworth Avenue), Worthing, BN12 4XB. The small admission charge of £3 helps pay for the room and free refreshments and goes towards supporting our membership. Doors open at 7.00 pm BST with the meeting starting at 7.30. NOTE: NO WORKSHOP EVENING IN AUGUST

I hope this does not cause too much inconvenience. Though summer nights remain bright there are some things going on. The Milky Way lays overhead during the summer nights and of course there are the Perseid’s though this year they may be a bit subdued due to the light of a waning gibbous Moon.

We can be found at: worthingastronomers.org.uk

And a reminder, as if one is needed – THERE WILL BE NO WORKSHOP MEETING IN AUGUST. This is due to the Goring Methodist Church requiring the facilities on both the first Friday and the second Friday (which was our back-up date.)

Contact addresses: Acting joint coordinators - info@worthingastronomers.org.uk – general society details, Janet Halls or Brian Halls

There are several astronomical groups in the coastal area of Sussex - several WA members are also members of the Adur Astronomical Society, who meet every first Monday of the month for a lecture regarding an astronomical subject. Details for the AAS can be found at Adur Astronomical Society.

treasurer@worthingastronomers.org.uk – donations contact Janet Halls acting-treasurer.

CONTRIBUTIONS AND UNSUBSCRIBING Contributions – written articles (word processed in .txt, .doc or .odt format), photographs, letters, advertising copy to the editor for the July issue should be in by June 15 and sent to the editor at the contact address: editor@worthingastronomers.org.uk

outreach@worthingastronomers.org.uk – events contact Steve Bassett, Mike Williams

If you no longer wish to subscribe to the group and cancel newsletters and other information, please send an email to: info@worthingastronomers.org.uk with 'Unsubscribe' in the subject line; we do not want our stuff to end up like spam littering your inbox.

editor@worthingastronomers.org.uk – newsletter content detail Brian Halls

website@worthingastronomers.org.uk – contact for website Perry Wilkins

Volunteers are always welcome: if you want to find out more, call 01903 521205 or drop us a line at the e-mail address above. If you like the newsletter or its content please feel free to distribute it to anyone you know who might be interested. Content is subject to copyright to the group and/or the individuals whose images or articles are used.

The Southern Astronomer No.106 – July/August 2017 LUNAR PHASES FOR AUGUST

ASTRONOMY

THIS MONTH July & August 2017 All times expressed as Universal Time (UTC – Co-ordinated Universal Time) unless otherwise stated which can be considered the same as GMT i.e Summer Time, minus 1 hour. Information given, unless otherwise stated is for the 15th of the month at 21.30UT. Lunar and other phenomena in the Quick View Diary are shown to the nearest hour where possible. Eclipses and meteor showers make for interesting evenings during the late summer.

JULY & AUGUST QUICK VIEW DIARY Day UT 1 01 3 21 6 04 9 04 16 19 21 17 23 09 25 07 27 00 28 22 30 03 31 15 Aug 1 2 7 12 15 18 19 21 25 29 30 31

18 18 19 01 04 18 18 08 08 10

Sunrise 03.53 Sunset 20.22 Moon: First Quarter Earth at furthest point in its orbit from the Sun (aphelion) Moon at apogee – furthest in its orbit from the Earth Full Moon Moon: Last Quarter Moon at perigee – closest in its orbit to the Earth New Moon Moon occults Mercury at 07.33.8UT Mars at conjunction Jupiter 3.0°S of Moon Mercury greatest elongation E (27°) Sunrise 04.27 Sunset 19.53 Moon: First Quarter

OBSERVING ECLIPSES

Sunrise 04.28 Sunset 19.51 Moon at apogee – furthest in its orbit from the Earth Full Moon – lunar eclipse Perseid Meteor shower maximum Moon: Last Quarter Moon at perigee – closest in its orbit to the Earth Venus 2.2°N of Moon New Moon – solar eclipse; partial from UK near to sunset Jupiter 3.3°S of Moon Moon: First Quarter Moon at apogee – furthest in its orbit from the Earth Sunrise 05.14 Sunset 18.53

t might be said that you wait for one eclipse and two come along together.

This is not unusual. The alignment of the nodes of the lunar orbit around the earth coincide this month with the direction of the Full Moon (as seen from the surface of the Earth)- the ‘full moon’ node to give a (partial) lunar eclipse. In the 14 or so days it takes the Moon to move from Full to the opposite node - ‘new moon’ node - is still opposite the Sun in the sky and we have a solar eclipse. On August 7 there will be a penumbral lunar eclipse – the Moon is passing through the lighter outer layers of the shadow of the Earth as it is cast into space and will not go the deep bloody-red a total umbral eclipse does (see below) though part of the Moon does pass into the umbra.

LUNAR PHASES FOR JULY

The Southern Astronomer No.106 – July/August 2017

Eclipses cont.

Half a lunar month passes by and the Moon is new and close to the node which is facing ‘sunwards’: a total solar eclipse occurs – on August 21.

he planet Venus is dominating the morning sky for those early risers amongst us. Low in the south east in the constellation of Taurus, the planet shines at a very bright -4m.

Even a small telescope with a magnification of about x60 will show the planet looking a little like a gibbous Moon (68% phase.) Greater magnifications will show the phase well plus any cloud detail and may show the unevenness of the terminator.

First the lunar eclipse. For us in the UK we get to see the latter stages of the Moon passing out of the penumbra. The Moon rises at 19.28UT – mid lunar eclipse is at 19.35UT – so the Moon will rise in eclipse and maximum will be when the Moon is barely clearing the horizon. We do get to see the latter stages of the eclipse – the penumbra clears the Moon at 20.50UT.

During the latter part of the month, Mercury is occulted at 07:33.8 by the very young crescent Moon on the morning of the 25th. Time is for Greenwich. A fascinating challenge!! Mars too, is close to the Sun – it is at conjunction at 0hUT on July 27.

The track of the solar eclipse on August 21 passes across the northern Pacific Ocean land falling the continental USA over Oregon just south of the border with Canada, heading down towards the south east eventually crossing the Carolina’s and into the Atlantic Ocean. The best place to see totality is at a place called Carbondale in Illinois.

The evening sky is dominated by the outer planets – Jupiter, Saturn, Uranus and Neptune. The ecliptic – the area of the sky the planets, Sun and Moon appear to travel through as seen from Earth is low in the sky during the summer nights so they are also low in the sky.

For us, only a small portion of the Sun is covered and that occurs just before sunset at 19.14UT.

Jupiter remains a fine object to look at as does Saturn. Uranus and Neptune are fainter star like objects just at the limits of naked-eye visibility – a reason why they were only discovered in ‘modern’ historical times. Both objects are readily seen in a pair of binoculars.

OBSERVING THE PLANETS:

July

Jupiter is already in the south western portion of the sky at sunset and it sets just after 23.00UT (or just after midnight BST.) Saturn is the planet to watch this month. Its retinue of satellites - Tethys, Dione, Rhea and Iapetus are the brightest to be seen in amateur equipment by they are not as well defined as the more familiar Galilean moons of Jupiter. Iapetus was discovered to be brighter on one side of its orbit around Saturn than at the other. This is due to brighter surface material on one hemisphere of the planet than the other and tidal locking of the satellite to its primary causes this orbital differences in brightening.

Planets in July

OBSERVING THE PLANETS:

AUGUST

he planetary situation changes little when compared with the previous month. Mercury is a poorly placed evening object, coming to its greatest eastern elongation on August 30 – a good western horizon just after sunset is required. Venus is prominent in the morning sky as well at -4.0m.

Planets in August

conjunction and is a morning object rising about 40 minutes before the Sun. Jupiter now sets as the sky begins to darken while Saturn remains the planetary object of attention, while the much fainter outer planets, Neptune and Uranus are in the low southern skies – the constellations Aquarius and Pisces respectively, rising mid-evening.

Mars is now past its

The Southern Astronomer No.106 – July/August 2017

Workshop Evening June 2nd “ADVENTURES IN ASTRONOMY: CHASING THE DARKENED SUN”

he presentation this month was originally scheduled for the August Workshop which has had to be cancelled due to the Church authorities having priority use of the Church hall at the time of our Workshop night. Zimbabwe 2001

It would have been quite fitting as August 11 is the 18th anniversary of the 1999 European Solar Eclipse that passed over the Cornish Peninsula and cut a swathe of darkness across most of western Europe.

eclipse on insects and animals and encountered for the first time a strong breeze, nicknamed the ‘eclipse wind.’ This phenomenon, though not always recognised or felt is caused by the drop in temperature caused by the lunar shadow as it crosses the landscape and produces a breeze or even a strong gust of wind ‘up track’ of its path.

It was also quite pertinent as there is to be a solar eclipse over the continental USA on August 21. In response to a question he asked, one member present that evening had plans to see the eclipse from Illinois where totality was to be at its best. Drawing on his experiences of observing this solar eclipse and three others, South Africa (Zimbabwe) 2001, North Africa (Libya) 2006 and, China 2008, our speaker Brian Halls briefly explained the causes of solar eclipse and went on to mention that solar eclipses were more than just the Sun going dim and then going ‘out’ for a short while before reappearing. Though these events do indeed occur there are other, more subtle phenomenon like the strange way light appears during the period leading up to the eclipse and just after; the eclipse wind that precedes totality and can wreak havoc to telescopes and cameras on tripods; watching the shadow of the Moon approach across the landscape; the way wildlife acts and, the strange appearance of ‘shadow-bands’. As with most things, the 1999 eclipse visible from a tiny portion of Cornwall though much awaited was clouded out, though those present that morning witnessed a darkening sky under leaden clouds that they have said they would never forget. Brian was in the English Channel, just north of the port of Le Havre on a ferry that had been deliberately diverted onto the eclipse track for the event. As this was his first solar eclipse he just sat and enjoyed the beauty of the event under fairly clear skies.

Libya 2006

Further effects of a solar eclipse were seen in the Libyan desert in march 2006. With an almost unobscured horizon the strange ‘twilight’ effect that occurs in the short period before totality was well seen as was the strange ‘shadow bands’ - the only time he has seen them. An analogue to shadow-bands is watching the shadow of ripples of water on the surface of the water on the floor of the pool. The accepted explanation is that shadow bands are actually shadows of air rippling – so perhaps not too far off of the analogue.

With an unobscured horizon it was strange to watch the dark shadow of the Moon approach from the west in the moments before totality. This was his first and it was not going to be his last.

August 8 2008 was the date of the start of the Beijing Olympic Games but not all travellers to that country were there for the sport. A week previous to the start of the Olympiad there was an eclipse of the Sun. The track of totality passed through the Russian Federation (maximum eclipse time was over Russia) and across into China. The location was on the Chinese side of the Gobi desert near to the eastern end of the old Silk Road trail. No shadow bands were observed, Brian suspects due to the lower angle of the Sun in the sky than it was in Libya (quite high); other shadow phenomenon were observed such as how the shadow of an object or even a person was blurry on one side but quite sharply ‘focussed’ on the other.

For the next solar eclipse – labelled by the media as the First Solar Eclipse of the Millennium – he had to travel slight farther than previously – to South Africa. This time and subsequently, he used the tour company Explorers and travelled under the auspices of the British Astronomical Association (BAA). The eclipse location for the Explorers group was to be a dried up river bed at the Maname School in the north of Zimbabwe (picture top right) close to the border with Zambia. The eclipse occurred on June 21- the winter solstice in South Africa but fortunately also the dry season which guaranteed (at his location at least) clear skies [Not always dry – on the flight back from Victoria Falls to the South African Republic, the plane flew into Johannesburg Airport during a torrential storm where the plane was struck by lightning while coming into land! BH]

Again the shadow of the Moon on the sky was apparent as it approached and departed the eclipse. That was his last solar eclipse to date. Brian mentioned that some of solar eclipses are not always easily accessible for travellers and if there is an organised trip to see one, the costs can be quite expensive. Saying that however, he had seen places that perhaps he would never have

It was in Zimbabwe that he was able to observe the effects of the

The Southern Astronomer No.106 – July/August 2017 Workshop Evening

During the question and answer session after the talk Brian explained to one question why solar eclipses differ in times – some seen if there had not been an organised trip – the mighty walls of the of the track pictures he had shown indicated maximum solar ruined city of Great Zimbabwe that gave its country its name; the eclipse. The answer is that the orbit of the Earth around the Sun is Roman city of Leptis Magna, the Greek colony of Cyrene sited on not perfectly circular and neither is the orbit of the Moon around the the Mediterranean coast of Libya; and in China the Forbidden City, Earth. Therefore the angular diameter of both Sun and Moon, the Palace of Heaven, the Terracotta Army and, both eastern and though similar changes over time. The result is that for a long western ends of the Great Wall. eclipse to occur, it is better for the Moon to have a larger angular diameter than that of the Sun. During our northern summer, the Sun Brian did however reassure that though some of solar eclipses in has a smaller angular diameter in the sky - 31° 29”. If that should the immediate future are not so near to home, in 2026 a total solar coincide with a New Moon that is at perigee (closest to Earth) then a eclipse would pass over northern Spain on August 12 and the sight longer period of totality would result. After further questions and of an eclipsed Sun at sunset would be breathtaking to see. answers, the main presentation of the evening came to a close. The remaining part of the meeting was a chance for everyone to catch On August 2 the following year the path of totality will cross north up with each other and basically have a good chat over tea and Africa (passing over Gibraltar) and passing over the Egyptian city of biscuits. Luxor before heading out to eclipse the Saudi city of Mecca. The next Workshop is October 6 – the group AGM and any Finally, if one got a chance to witness a total solar eclipse, take it as presentations that members may want to make. this is one of natures greatest displays.

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OBSERVING:

METEORS & COMETS

ctive from mid-July is the Perseid meteor stream which reaches maximum on August 12/13. The peak takes place during the early evening in the UK. With the full Moon on the 7th with last quarter on the 15th, there is the strong likelihood of daylight conditions and bright moonlight after sunset interfering with the more brighter aspects of the maximum. The stream continues until about the 24th. The best time to view the Perseids, and most other meteor showers for that matter, is when the sky is the darkest. The best time to view meteor showers is after mid-night and before dawn.

The Perseid radiant early morning August 13

The Perseids are not the only meteors to be visible this time of year. A lesser shower is the κ-Cygnids which appear between August 3 to 25 (chart left.) The radiant position is plotted every 5 days in August. With Cygnus high in the sky, this would be a good shower to observe except the average (ZHR) is 3 per hour and observing for 2017 may be only between August 6 – 19! As the International Meteor Organisation say in their notes for this year, “..the shower may not behave as it is ‘supposed to’!”

The Southern Astronomer No.106 – July/August 2017 Meteor & Comets

C/2015 V2 (Johnson) makes an appearance low in the south-west sky as the sky darkens – laying between Virgo and Libra a 7.4m object mid-July.

Last night I lay in bed looking up at the stars in the sky and I thought to myself, where the heck is the ceiling?

It is the only bright comet visible during July and August.

OBSERVING REPORT:

THE SUN

or a rare few die hard amateur astronomers, the summer period cannot be over and done with quick enough so the long dark evenings will return and the chances to look at many deep sky objects during the long darkness of night returns. For others, it is the best time to do maintenance work on the ‘scopes, mounts or if they are lucky, their observatories. On the other side of the coin, the long days of summer allow one celestial object to be observed for much longer periods – the Sun. The long dry and clear spells of the last couple of months have been a useful time for observing the Sun. The Sun, as has been noted in these pages over the last few years or so is ‘quiet’ - few sunspot groups and those that do appear seem to be smaller than one would like but, sunspot activity is going on all the same.

The Sun in h-alpha in June

Not all solar activity is just sunspots. The image above taken by Steve Willeter shows the Sun active in other ways.

One interesting feature – noted but not quite full understood - is for active regions of the Sun to be fixed by longitude rather than being evenly distributed across the solar globe. A point in case is occurring at the moment.

The dark features are filaments – arches of hot solar material caught up in magnetic fields. Often they are associated with sunspot groups but some of them here do not appear to have any sunspot groups to be associated with.

To broadly generalise, the month begins ‘spotty’, then it peters out for a week or several days before once more becoming spotty and then fading again. This coincides with spotty areas of the Sun bought into view by the Sun’s rotation for 14 days or so and then departing and then returning in another fourteen days or so.

Sunspots are are the visual manifestation of twists and kinks in magnetic fields which break through the visual ‘surface’ of the Sun (the photosphere.)

What causes this is debated by solar scientists but it shows that the Sun is not uniformly active. Another interesting feature of the last several months is that sunspot activity has been very much situated in the northern solar hemisphere, hardly any spots or groups appearing in the southern.

These break through points cause cooling and the photosphere darkens – sun spot! Using a special telescope such as the hydrogen alpha telescope such as the one Steve used, we are able to glimpse the portion of the Sun that exists above the photosphere where the filaments can be seen.

As was proved by Hale over a hundred years ago, the magnetic fields of sunspots and groups (and areas of the Sun where no spots appear) differs between the hemispheres. At present, the leading sunspot in the northern hemisphere has a negative value while the following spot is positive. The reverse is true in the south. At a point in the near future, this will reverse and spots that show this new inversion are considered to be spots belonging to the next solar cycle – they usually appear as high latitude spots, while the spots of the previous cycle are at lower latitudes either side of the solar equator.

As a note, when filaments reach the edge of the Sun and can be seen in profile at the Sun’s edge they are referred to as prominences. AS USUAL A WORD OF CAUTION OBSERVING THE SUN IS A FASCINATING PASTIME: HOWEVER CARE MUST BE TAKEN AT ALL TIMES AS THE SUN, THOUGH A STAR, IS NEAR TO US AND A SOURCE OF HEAT AND RADIATION THAT COULD PERMANENTLY DAMAGE EYESIGHT IF PRECAUTIONS ARE NOT FOLLOWED

Will we see a return to large sunspot groups during the next cycle (predicted to appear about 2020)? The experts get it wrong almost all the time – the present lacklustre cycle was predicted to go off the scale where sunspots are concerned. In fact it is the opposite. The predictions for the next solar cycle (number 25) is for more of what we are having (or not having) as sparse sunspot activity is predicted.

If you are interested in looking at the Sun using safe methods, write to one of the addresses on page two or contact the group Facebook page for advice.

What will happen. Who knows? Not knowing what is around the corner makes solar astronomy for a fascinating aspect of amateur astronomy.

The Southern Astronomer No.106 – July/August 2017

The sky mid-evening from Sussex at 21.30 UT, July 31

slightly different map than normal this time. Normally we pick a night sky view about mid month but in this issue, to reflect that we are covering two months, the night sky at the end of July/beginning of August would be best.

objects. Many of these will be scientific probes measuring and imaging the planet below and have official names or designations. Others will officially not exist – intelligence gathering objects spying on us.

Nearly overhead, the Milky Way with all the various wonders will be displayed and a target for astro images out there.

The ISS rises in the west and sets in the east normally but some of these artificial satellites will trace paths across the sky east to west, west to east, north to south and, south to north, and all compass directions in between.

Of course you do not have to take photographs of the night sky. There is nothing more nicer than after a hot day than to lay, looking up at the sky, watching the stars unfold before your eyes.

These are of course nearby objects, orbiting us a few hundred kilometres up, but beyond them are the stars, clusters and nebulae that make up our local Milky Way galaxy.

A pair of binoculars will show many, many, more stars than you will see with your unaided eye. On nights like these, moving stars will be quite prominent – artificial satellites! Some like the International The evenings are slowly drawing in now. The beauty of a summer Space Station will be bright, while others will be faint star like nights sky should not be missed.