MAC April 2012 Magazine by MAC Realta

Midlands Astronomy Club Magazine

Sky Guide - Beginnerâ&#x20AC;&#x2122;s targets for April

Issue 33- April, 2012

General notes As spring starts to quicken everything into life again, so meteor activity begins to pick up too. The first northern shower of any note is the Lyrids which has no Moon this year. April has something of a reputation for producing more than its share of sporadic fireballs, though some of this impression may result from the occasional spectacular Lyrid fireball. Lyrid meteors can be seen from April 16-25, and the shower should peak on April 22. The year there is a Waning Gibbous moon. Shower gazing conditions will not be ideal. The moon will obstruct all but the brightest of Lyrid meteors. The average ZHR is 18, and tends to be lower the further the maximum happens away from the "ideal" time. Lyrids are medium-fast meteors, and can be very bright sometimes. Telescope Targets We'll start the month off in Cancer with M44 (The Beehive Cluster). To find M44, find Regulus (the bright star in the backwards question mark in Leo) and Pollux in Gemini (the star closer to Regulus in the twins). About halfway between these two is M44. M44 can be seen with the naked eye from a dark site. Use your lowest power eyepiece to try and get the entire cluster into view. M44 makes a nice

Above: A sky chart showing the centre of the Lyrid meteor shower. Look for the star Vega as a guide. binocular target. M44 is a loose open cluster containing about 400 stars and is located approximately 500 light-years away.

Above: The Beehive Cluster is an open cluster in the constellation Cancer and is one of the nearest open clusters to the Solar System.

Club Notes Club Observing: The next club meets every 1st and 3rd Saturday of the month for our observing sessions held in the MAC grounds. If you wish to be informed of these sessions please email your name and mobile number to midlandsastronomy@gmail.com who will confirm if the session is going ahead (depending on weather).

MAC is a proud member of

Above: Cancer is one of the twelve constellations of the zodiac. Its name is Latin for crab and it is commonly represented as such. Cancer is small and its stars are faint. It lies between Gemini to the west and Leo to the east, Lynx to the north and Canis Minor and Hydra to the south. Next we'll move on to another open cluster in Cancer, M67. To find M67, again we'll use Regulus, but this time Procryon will be the other star. About halfway between these two stars is M67. M67 is one of the older open clusters with age estimates from 5 - 10 billion years old. It contains about 500 stars and is located approx. 2500 light-years from us. Next, we'll move on to a galaxy. M51 (The Whirpool Galaxy) is one of the skies premier galaxies. Through scopes of 8" or larger, the spiral arms become evident and large scopes show the galaxy in all of it's spiral glory. To locate M51, find Alkaid (the star at the end of the Big Dipper's handle). Just below Alkaid is M51. Also visible with M51 is the companion galaxy NGC 5195. You'll need a very dark site to spot these, but it's well worth the trip. Distance estimates to these galaxies range from 15 million to 40 million light-years away. Moving back over toward Leo, find the triangle of stars to the left of the backwards question mark. The point of the triangle

Above: The M51 galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars. points at the magnificent Virgo Cluster. I could take pages trying to explain which galaxies are which here so I'll just say point your scope in that direction and scan the area. Even in small instruments several galaxies at a time will be visible in the same field of view. General notes Check out www.heavensabove.com for the latest passes of the International Space Station and satellites, details of Space Shuttle launches and passes and for details of Iridium Flare activity. Clear skies and good hunting!

By Kevin Daly http://members.aol.com/kdaly10475/index.html

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Latest Astronomy and Space News Kids Astronomy Quizzes and Games Monthly Sky Guide Internet Highlights

Midlands Astronomy Club Magazine

Enjoy the sights of the Northern lights .................................. 7 Oxygen atmosphere around Saturn’s moon Dione ................. 8 Why does the “Man in the Moon” face Earth?........................ 8 The Owl Nebula .................................................................. 9

Kids Section Kids Korner ....................................................................... 10 Front cover image: Large galaxies and faint nebulae highlight this deep image of the M81 Group of galaxies. First and foremost in the wideangle 12-hour exposure is the grand design spiral galaxy M81, the largest galaxy visible in the image. M81 is gravitationally interacting with M82 just below it, a big galaxy with an unusual halo of filamentary red-glowing gas. Around the image many other galaxies from the M81 Group of galaxies can be seen. This whole galaxy menagerie is seen through the faint glow of an Integrated Flux Nebula, a little studied complex of diffuse gas and dust clouds in our Milky Way Galaxy.

Quizzes and Games Exercise your brain ............................................................ 11

Monthly Sky Guide Beginners sky guide for this month .................................... 12

Internet Highlights Special content only available with the online version of the magazine ................................................................ 13

4300 years 4.3 months 4.3 years 43 years

4 9

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3. What is a pulsar? None of these The centre of a galaxy A spinning neutron star that emits radio waves A supermassive Black Hole

8. Which planet has carbon dioxide?

Mars Earth Mercury Venus

4. Approximately, how 9. What is the pressure at the centre of the Earth? much time does light from the Sun take to 37 million atmospheres reach the Earth? 3.7 million atmospheres 8 mins and 20 secs 5 million atmospheres 9 mins and 30 secs 370 million atmospheres 4 mins and 30 secs 1 min and 30 secs 10.How many kilometres is one light year? 5. Which is the 4th biggest 946 billion km planet in our solar 9.46 million km system? 9.46 billion km Neptune Earth Uranus Mars

9460 billion km

Confused??? Check your answers on this page.

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Credit & Copyright: Nicolás Villegas

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Check your answers

Answer 1: The correct answer was Galaxy. Stellar systems are like Solar systems.

Mercury poles give up hints of water ice ............................... 6

Methane, Helium Methane, Oxygen Hydrogen, Helium

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Answer 6: The correct answer was A star near (relatively) to our Sun. Some say that Alpha Centauri is the star nearest to the sun while some others say that it is Proxima Centauri. Did you know that a spherical 'cloud' exists beyond Pluto? Well, it is called the Oort Cloud. It is said that there are billions of comets there.

Fledgling stars flicker in the heart of Orion ............................ 6

Answer 7: The correct answer was 4.3 years. That shows how far it is from us.

Astronomers discover quasars acting as gravitational lenses .. 5

Answer 2: The correct answer was Hydrogen, Helium. Inside the protostar's core, nuclear fusion takes place and the force of the blast blows away surrounding gas and dust and the star now forms a T Tauri Type star. After that, it enters the main sequence period. Our Sun has been in the main sequence period for about 5 billion years.

Citizen scientists reveal a bubbly Milky Way .......................... 5

Answer 8: The correct answer was Mercury. Mercury has an extremely thin atmosphere with no trace of CO2. Its exact opposite, Venus has enormous amounts of this gas.

You can see more about the club and its events on www.midlandsastronomy.com or contact the club via e-mail at midlandsastronomy@gmail.com Meetings are informal and are aimed at a level to suit all ages.

Rare rain on Titan; once every 1,000 years ........................... 4

Answer 3: The correct answer was A spinning neutron star that emits radio waves. 'Pulsar' stands for PULSating stAR. There is no special name for supermassive black holes. The centre of distant galaxies are intensely bright objects called Quasars (Quasi-Stellar Radio Sources).

Oldest alien Planets found - born at dawn of universe ........... 4

Answer 9: The correct answer was 3.7 million atmospheres. 3.7 million atmospheres means the pressure exerted by the atmosphere multiplied by 3.7 million. The temperature is around 4000 degrees Celsius! Although at such a high temperature, the inner metallic core should be liquid, the immense pressure causes it to be solid!

Space observations of Mercury transits yield precise solar radius ............................................................. 3

SUDOKU

Answer 4: The correct answer was 8 minutes and 20 seconds. We all know that the distance travelled by light in one year is called a light year. The distance travelled by it in about 8 minutes and 20 seconds is called an 'Astronomical Unit' (AU)- it is the average distance between the sun and the earth, about 150 million km.

New Supernova found "Next Door” ....................................... 3

is Proxima 1. What is a vast collection 6. W h a t Centauri? of billions of stars, dust and hydrogen called? A satellite (the largest) of Planets Neptune A comet (from the Oort's None of the above Cloud) Stellar System A large asteroid Galaxy A star near (relatively) to our Sun 2. A protostar (a star in the early stage of its life) is formed by t h e 7. How much time does light from the second aggregation of which nearest star to Earth two predominant gases? take to reach it? Hydrogen, Oxygen

Answer 10: The correct answer was 9460 billion km. The speed of light is approximately 300,000 km/s. One light year is therefore - 300,000 x 3600 x 24 x 365 which is equal to about 9460 billion km.(9.46 x (10 to the power of 12) km). Big calculation, isn't it?

Latest Astronomy and Space News

All are welcome to attend. It also holds infrequent Observing Nights at its Observing Site in Clonminch, or at a member’s house (weather permitting) on the first Friday of every month..

Exercise your brain

contents

Answer 5: The correct answer was Neptune. The decreasing order of the size of the planets is - Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, Pluto.

MAC meets on the first Tuesday of the month in the Presbyterian Hall, High Street, Tullamore from 8pm.

Midlands Astronomy Club Magazine

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Midlands Astronomy Club Magazine

Kid’s Korner Meteor shower! If it's time for a meteor shower, you won't need a telescope, binoculars, or a high mountain to have a "star gazing" party. You might need a warm sleeping bag and an alarm clock to wake you in the middle of the night. But then just lying down in your own back yard will put you in the perfect spot to enjoy a great show.

A new supernova has been found in the nearby galaxy M95, astronomers have confirmed, and it's one of the closest stellar deaths yet witnessed.

Earth makes its journey around the Sun, its orbit crosses the orbit of a comet, which means Earth smacks into a bunch of comet debris.

Why would Earth encounter many But not to worry! meteoroids at once? Well, comets, The meteoroids are usually small — like Earth and the other planets, from dust particle to boulder size. also orbit the Sun. Unlike the They are almost always small nearly circular orbits of the planets, enough to quickly burn up in our the orbits of comets are usually atmosphere, so there's little chance quite lopany of them sided. As a will strike comet gets E a r t h ' s closer to surface. But the Sun, there is a some of its good chance icy surface that you can boils off, s e e a releasing beautiful lots of shooting star particles of show in the If your lucky you’ll see a bright streak of light dust and middle of the something like this as the meteor burns up in the rock. night!

What is a meteor shower? A meteor is a space rock—or meteoroid—that enters Earth's atmosphere. As the space rock falls toward Earth, the resistance—or drag—of the air on the rock makes it extremely hot. What we see is a "shooting star." That bright streak is atmosphere. not actually the rock, but rather the This comet debris gets strewn out glowing hot air as the hot rock zips along the comet's path, especially through the atmosphere. in the inner solar system (where When Earth encounters many we live) as the Sun's heat boils off meteoroids at once, we call it a more and more ice and debris. Then, several times each year as meteor shower.

New Supernova found "Next Door”

In the case of a meteor shower, the glowing streaks may appear anywhere in the sky, but their "tails" all seem to point back to the same spot in the sky. That's because all the meteors are coming at us at the same angle, and as they get closer to Earth the

effect of perspective makes them seem to get farther apart. It's like standing in the middle of railroad tracks and seeing how the two tracks come together in the distance. Meteor showers are named for the constellation where the meteors appear to be coming from. So, for example, the Orionids Meteor Shower, which occurs around October 21 each year, appear to be originating near the constellation Orion the Hunter. Plan ahead Here are dates of major meteor showers. Peak viewing times will vary by a day or two each year. Keep in mind: If the Moon is full or near full, you may not see many meteors. Some years are better than others for numbers of meteors per hour.

Annual Meteor Showers Quadratids - January 3/4 Lyrids - April 21/22 Perseids - August 12/13

On M a r c h 1 6 p r ofe s s ion a l astronomers and amateur observers detected the bright point of light on the outskirts of M95, a barred spiral galaxy in the constellation Leo, the lion. Since then, various teams have been watching the object closely. Based on observations from around the world, the International Astronomical Union announced on Tuesday that the light is definitely an exploded star, now called SN 2012aw.

happened to be taking pictures of M95 before SN 2012aw appeared.

Most supernovae are discovered in much more distant galaxies, so the explosions are not detected until they've reached close to maximum brightness, said Ulisse Munari of Italy's National Institute of Astrop hys ics. But the ne w supernova is in a galaxy just 37 million light-years away—practically next door in astronomical terms.

According to Munari, astronomers "could take this opportunity to investigate how the initial shock propagated within the stellar structure" during the resulting explosion. It's fairly surprising the pre-supernova images even exist, Munari added.

"The detection threshold has been broken already," Munari added, and the supernova should get even brighter in the coming days. What's more, some amateur astronomers

Combined with an ongoing catalogue of new images, the older shots will allow astronomers to study the very early stages of a supernova—perhaps helping to unravel what happens in the first hours of a star exploding. For instance, SN 2012aw is what's known as a Type II supernova, the result of a very massive star's core collapsing.

Mars is currently half a degree from M95 in the night sky, and from our vantage point the planet is a hundred thousand times as bright as the whole galaxy.

Mars would have made M95 a less attractive target for many stargazers, Munari said, and "most observers [likely] turned their attention away from M95, waiting for Mars to move a greater distance away." But some night-sky photographers, including Parijat Singh of Arizona, persisted in keeping their telescopes trained on M95. "I didn't realize Mars would contaminate my images," said Singh, who had picked the galaxy almost at random. Not until taking nearly an hour's worth of M95 images, pre-supernova, did Singh realize that Mars was messing with his shots. In the end, though, the pictures came out clear enough to see the galaxy. "It was lucky," the National Institute of Astrophysics' Munari said. www.nationalgeographic.com

That means light pollution from

Space observations of Mercury transits yield precise solar radius

A group of scientists from Hawaii, Brazil, and California has measured the diameter of the Sun with unprecedented accuracy by using a spacecraft to time the transits of the planet Mercury across the face of the Sun in 2003 and 2006.

The measurement was achieved by using the solar telescope aboard a NASA satellite, thereby bypassing the blurring caused by Earth’s atmosphere that occurs when observations are made from the ground.

They measured the Sun’s radius as 696,342 kilometres with an uncertainty of only 65km. This was achieved by using the solar telescope aboard a NASA satellite, thereby bypassing the blurring caused by Earth’s atmosphere that occurs when observations are made from the ground.

Orionids - October 21/22 Leonids - November 17/18 Geminids - December 13/14

Mercury's path across the solar disk as seen November 8, 2006.

Marcelo Emilio, Jeff Kuhn, and Isabelle Scholl from the University of Hawaii Institute for Astronomy in collaboration with Rock Bush from Stanford University, California, made the measurements of the

Above: The spiral galaxy M95, as seen by the Very Large Telescope in Chile before the supernova appeared. The smaller image shows the same galaxy during the supernova. Sun’s size with the Michelson Doppler Imager (MDI) aboard NASA’s Solar and Heliospheric Observatory (SOHO). “Transits of Mercury occur 12-13 times per century, so observations like this allow us to refine our understanding of the Sun’s inner structure and the connections between the Sun’s output and Earth’s climate,” said Kuhn. The team is preparing to observe the transit of Venus across the Sun June 5. They expect these observations will improve the accuracy of their solar size measurement even further. www.universastronomy.com

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Midlands Astronomy Club Magazine

Oldest alien Planets found - born at dawn of universe

The Owl Nebula The Big Dipper, that most famous of asterisms, reaches nearly overhead in mid-northern latitudes in the early months of northern spring. The Dipper and its host constellation Ursa Major hold many excellent sights for stargazers. One of the most intriguing is M97, the famous Owl Nebula.

Two huge planets found orbiting a star 375 light-years away are the oldest alien worlds yet discovered, scientists say. With an estimated age of 12.8 billion years, the host star—and thus the planets—most likely formed at the dawn of the universe, less than a billion years after the big bang. "The Milky Way itself was not completely formed yet," said study leader Johny Setiawan, who conducted the research while at the Max-Planck Institute for Astronomy in Heidelberg, Germany. During a recent survey, Setiawan and colleagues found the signatures of the two planets orbiting the star, dubbed HIP 11952. Based on the team's calculations, one world is almost as massive as Jupiter and completes an orbit in roughly seven days. The other planet is nearly three times Jupiter's mass and has an orbital period of nine and a half months. It's possible the planets are much younger than they seem if the worlds formed long after their star was born—but such a scenario is unlikely, the team says.

"Usually planets form just shortly after the star formation," Setiawan said. "Second-generation planets might also form after a star has died, but this is still under debate." Setiawan and colleagues found the ancient planets using a technique called radial velocity, in which astronomers watch for periodic wobbles in a star's light due to the gravitational tugs of orbiting worlds. The discovery indicates that planet formation in the early universe was possible despite the fact that stars in existence back the n were metal-poor— the astronomy term for stars lacking in elements heavier than hydrogen and helium. In the case of HIP 11952, "its iron abundance is only about one percent that of our sun," Setiawan said. The idea of planets springing from such a stellar makeup runs counter to a widely accepted theory called the accretion model, which says that heavy elements are needed to form planets.

Rare rain on Titan; once every 1,000 years Even though there are lakes and rivers of liquid hydrocarbons on the surface of Saturn’s moon Titan, the rains that feed them may come few and far between. According to data gathered by NASA’s Cassini mission, parts of Titan might not see rain for more than 1,000 years. Rain on Titan?! It sounds bizarre, but scientists have observed a complex cycle of liquid on Titan, with lakes and rivers, clouds, and the rain that must feed them. But on Titan, where surface temperatures plunge to -179C, we’re not talking about water. The whole hydrological cycle runs with methane: methane lakes, methane rivers, and methane rain. And it appears that the rain on Titan can be extreme, with deep river

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channels that must have had enormous flows for brief periods. But this rain must also be rare. In all of its observations of Titan, Cassini only spotted two instances of darkened regions that might have indicated rainfall. Dr. Lorenz presented his estimates of the Titan rainfall, and the need for a new mission that could study it. Dr. Lorenz is one of the scientists involved with the proposed Titan Mare Explorer

bula in nebula Owl Ne The planetary ry ve a as regarded Ursa Major is itude gn ma th 16 e Th nice object. s inate the cloud central star illum like eyes. holes and carve two

A young planetary nebula, M97 is a speeding cloud of glowing gas ejected by a small dying star. In a small scope under dark sky, the nebula resembles the eyes of wise old barn owl gazing out of the interstellar darkness.

Above: An artist's rendering of the oldest known planets orbiting their star. Even gas giants like Saturn and Jupiter require heavy elements to take shape, the thinking goes, because they are built upon solid cores. The accretion theory has so far been backed up by observations: Most of the planet-harbouring stars discovered to date are relatively young and have moderate to high amounts of metals. But there may be an observational bias, Setiawan said: Astronomers may think the accretion model is correct because planet hunters (TiME) mission; one of three shortlisted missions that might be turned into NASA Discovery missions. If selected, TiME would travel to the Saturn system, and land in Ligeia Mara, a large lake on the surface of the moon. It would search for rainstorms on the descent – an extremely unlikely event – and then watch the skies for evidence of rainfall. It would be able to “hear” rain falling directly onto it, and in the liquid around it. TiME would also be equipped with instruments that would let it see cloud formation, rain shafts, and even methane rainbows. Assuming the rain shafts are 10 km wide, and would be observable at distances of 20 km, the lander should be able to detect rainstorms within a 1200 km2 area. According to Dr. Lorenz “We might expect a 50% chance for a lander to be rained on directly in a 2500hr

have been targeting mostly young, sunlike stars. "To verify this issue, it is necessary to do a planet-search survey around [older] metal-poor stars," Setiawan said. Despite the newfound planets' longevity, it's unlikely the worlds will survive for another 13 billion years. The parent star will soon transform into a red giant, Setiawan said, one of the last stages of a sunlike star's life. During this stage, the star will swell in size and most likely engulf any nearby planets.

The Owl Nebula’s name was inspired by a sketch made by the 19th-century astronomer Lord Rosse, who observed the nebula with his home-made (!!!) 72-inch telescope in Ireland. Rosse’s sketch reveals, as do modern images, two large central markings that resemble the eyes of an owl.

modern stargazers, who are scourged by light pollution, rank the object as one of the most challenging of all sights on the Messier list. That’s because the 9th -magnitude nebula is spread over a patch of sky about five times the size of Jupiter’s disk. Light pollution renders the object nearly invisible, though I’ve seen the nebula from the fish-grey skies of downtown Ottawa.

In suburban skies or darker, the object is much easier. Once you locate the nebula, experiment with your eyepieces to get the best view. Your best bet is W h i l e M e s s i e r a n d h i s magnification of 100-120x, and contemporaries observed M97 with you’ll need a 6-inch or larger scope tiny 2 to 4-inch instruments, to see the “eyes”. A UHC or OIII

Estimates indicate that regions near Titan’s poles see rainfall for 10-100 hours every Titan year (30 Earth years). But the drier parts of the moon might not see more than a single rainfall every 1,000 years.

Look for the Owl Nebula just below the bowl of the Dipper, about 2.3 degrees east-southeast of Mirak, or beta Ursa Majoris.

texture and shape in a 4-inch or larger scope, and lies within the same low-power field of view as M97. www.oneminuteastronomer.com

At 14th-magnitude, the nebula’s central star can be glimpsed in a 10 -inch or large scope. The star lies exactly between the two “eyes”. M97 lies about 1600 light years from Earth. The central star began ejecting the nebula about 6,000 years ago, and it will remain as a lone white dwarf star, a glowing ember about the size of the Earth, that will slowly cool over the next many billions of years.

www.nationalgeographic.com

mission”. While the weather system on Titan is similar to Earth, it probably has some significant differences, which Cassini observations have hinted at. Although there were possible storms seen in 2004, there was a huge gap until 2010. After the “storm”, the surface of Titan was changed with a large darkened area that could indicate saturation of liquid on the surface. These ponds seemed to dry up in future observations.

filter help bring out the elusive detail in this object.

Above: Position of M97 near the star Merak in the Dipper's Bowl

Bonus Object: About 1/3 the distance between the Owl Nebula and Mirak lies the mottled, cigarshaped galaxy M108. The 10thmagnitude galaxy reveals some

To help find your way around the night sky, Skymaps.com makes available for free each month a map of the night sky. The Evening Sky Map is suitable for all stargazers including newcomers to astronomy and will help you to: • identify planets, stars and major constellations.

• find sparkling star clusters, wispy nebulae & distant galaxies.

• locate and follow bright comets across the sky.

• learn about the night sky and astronomy.

www.universetoday.com

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Midlands Astronomy Club Magazine

Oxygen atmosphere around Saturn’s moon Dione

Citizen scientists reveal a bubbly Milky Way

NASA’s Cassini spacecraft has discovered a tenuous atmosphere of molecular oxygen ions around Saturn’s moon, Dione. The satellite’s atmosphere was initially detected in April 2010 by an instrument called the Cassini Plasma Spectrometer (CAPS). At the time, the Cassini probe was making its second close fly-by of the moon, passing just 503 kilometres above its surface.

A team of volunteers has pored over observations from NASA’s Spitzer Space Telescope and discovered more than 5,000 “bubbles” in the disk of our Milky Way Galaxy. Hot, young stars blow these bubbles into surrounding gas and dust, indicating areas of new star formation.

To an observer on the surface of Dione, the atmosphere would pretty much go unnoticed. It is so thin that there is only one oxygen ion per 11 cubic centimetres of space, which is as rarefied as Earth’s atmosphere at an altitude of 480 kilometres. Due to this low density, Dione’s atmosphere can also be thought of as an exosphere, similar to the very uppermost layers of a typical planetary atmosphere. It is thought tha t Dione’s atmosphere is formed by a process called sputtering, which occurs when charged particles from Saturn’s magnetosphere collide with Dione’s surface. These collisions cause oxygen ions to be ejected from the moon’s surface, and the thin exosphere to be formed. Once liberated from the moon’s surface, Saturn’s magnetic field then strips the oxygen ions away from Dione altogether, preventing the atmosphere from getting thicker. Astronomers are also investigating the possibility that geological processes on the moon may be

While Dione’s exosphere is a significant discovery, the moon itself is not unique in this regard. Saturn’s second largest satellite, Rhea, has also recently been shown to have a thin atmosphere, comprised of oxygen and carbon dioxide. “We now know that Dione, in addition to Saturn’s rings and the moon Rhea, is a source of oxygen molecules,” says Robert Tokar, a Cassini team member and Above: At 1122 km in diameter, the lead author of the paper Dione is the 15th largest moon in the announcing the discovery. “This Solar System, and is more massive shows that molecular oxygen is than all known moons smaller than actually common in the Saturn system and reinforces that it can come from a process that doesn’t bodies in the Solar System. Dione involve life.” has a slightly chilly average surface temperature of -186 degrees With a diameter of 1,100 Celsius, and lies within Saturn’s kilometres, Dione is the fourth- diffuse E-ring, where it orbits the largest of Saturn’s moons, and was planet once every 2.7 days. discovered in 1684 by Giovanni Cassini. It is a small, frozen world, The Cassini space probe has been comprised mostly of rock, covered in orbit around Saturn since 2004, in a thick layer of water ice, which wher e it has ma de ma ny makes it one of the most reflective discoveries about the planet and its

Why does the “Man in the Moon” face Earth? When we look at the Moon, we see these amazing variations of light and dark. And depending on your orientation on Earth, you might see the famous “Man in the Moon”, or maybe the “Rabbit in the Moon”. The darker areas are known as maria, smooth lava fields created by ancient volcanic eruptions on the Moon. But why do we see this face of the Moon, and not a different side? The Moon’s rotation is tidally locked to the Earth. This means that the Moon always presents the same side to us, completing one orbit around the Earth in the exact same amount of time it takes to turn once on its axis. From our perspective, the Moon never rotates, always displaying the “Man in the Moon”.

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Upwards of 35,000 “citizen scientists” sifted through the Spitzer infrared data as part of the online Milky Way Project to find these telltale bubbles. The volunteers have turned up 10 times as many bubbles as previous surveys so far.

causing the release of oxygen ions.

When the first spacecraft were sent from Earth to orbit the Moon, they sent back surprising photographs that revealed a completely different landscape from what we’re used to. Instead of the dark splotches of lunar maria we see on the near side – the “Man in the Moon” – the far side is merely covered in craters.

So why is the maria-side facing us, while the crater-side faces away? Is it just a coincidence? Researchers from the California Institute of Technology think that it’s not about luck at all, but the way the Moon’s rotation slowed down after its formation. Oded Aharonson, a professor of planetary science at Caltech, and his team created a simulation that calculated how the rotation of the Moon slowed down after its formation. Although the Moon looks like a sphere, it actually has a slight bulge. And billions of years ago, when the Moon was rotating much more quickly, showing its entire surface to the inhabitants of Earth, the Earth’s gravity tugged at this bulge with each rotation, slowing it down slightly each time until the

moons. The spacecraft has recently made an even closer fly-by of Dione, passing just 99 kilometres above its surface on 12 December 2011, which will likely be the closest that Cassini will ever get to this particular moon. Scientists are currently analysing the data recorded by the probe’s Ion and Neutral Mass Spectrometer (INMS) in order to discover if any other elements are present in the newly discovered atmosphere. www.skymania.com

Moon’s rotation was completely stopped from our perspective. In every simulation that the Caltech did, thanks to the orientation of this lunar bulge, either the Moon’s maria -side or crater-side ended up facing Earth. But the rate at which it slowed down – how fast it dissipated its rotational energy – defined our chances of seeing the “Man in the Moon”. If the Moon slowed down quickly, it would have been a 50/50 chance. But because the Moon slowed down more gradually, we had a much higher chance of seeing the mariaside as the final result. The mariaside was twice as likely to be our final view over the crater-side. www.universetoday.com

“These findings make us suspect that the Milky Way is a much more active star-forming galaxy than previously thought,” said Eli Bressert from the European Southern Observatory, Germany, and the University of Exeter, England. “The Milky Way’s disk is like champagne with bubbles all over the place,” he said. Computer programs struggle at identifying the cosmic bubbles, but human eyes and minds do an excellent job of noticing the wispy arcs of partially broken rings and the c irc les -w ithin-c irc le s of overlapping bubbles. The Milky Way Project taps into the “wisdom of crowds” by requiring that at least five users flag a potential bubble before its inclusion in the new catalog. Volunteers mark any candidate bubbles in the infrared Spitzer images with a sophisticated drawing tool before proceeding to scour another image.

index finger held at arm’s length, and your arms opened to the sky span about 130°. The surveys peer through the Milky Way’s disk and right into our galaxy’s heart. The bubbles tagged by the volunteers vary in size and shape, both with distance and due to local gas cloud variations. The results will help astronomers better identify star formation across the galaxy. One topic under investigation is triggered star formation in which the bubbleblowing birth of massive stars compresses nearby gas that then collapses to create further fresh stars. “The Milky Way Project has shown that nearly a third of the bubbles are part of hierarchies where smaller bubbles are found on or near the rims of larger bubbles,” said Matthew Povich from Penn State, University Park. “This suggests new generations of star formation are being spawned by the expanding bubbles.”

Above: A team of volunteers from the general public has pored over observations from NASA's Spitzer Space Telescope and discovered more than 5,000 b" ubbles"in the disk of our Milky Way Galaxy. Variations in the distribution pattern of the bubbles intriguingly hint at structure in the Milky Way. For example, a rise in the number of bubbles around a gap at one end of the survey could correlate with a spiral arm. Perhaps the biggest surprise is a drop-off in the bubble census on either side of the galactic centre. “We would expect star formation to be peaking in the galactic centre because that’s where most of the dense gas is,” said Bressert. “This project is

bringing us way more questions than answers.” In addition, the Milky Way Project users have pinpointed many other phenomena, such as star clusters and dark nebulae, as well as gaseous “green knots” and “fuzzy red objects.” Meanwhile, the work with the bubbles continues, with each drawing helping to refine and improve the catalogue. www.astronomy.com

based on the collective brightnesses of its stars. However, gravitational lensing candidates are invaluable for estimating the mass of a quasar’s host galaxy because the amount of Astronomers using NASA’s Hubble Space Telescope have found distortion in the lens can be used to estimate a galaxy’s mass.

Astronomers discover quasars acting as gravitational lenses

“The Milky Way Project is an several examples of galaxies containing quasars, which act as attempt to take the vast and beautiful data from Spitzer and gravitational lenses, amplifying and distorting images of galaxies make extracting the information a aligned behind them. fun, online, public endeavor,” said Robert Simpson from Oxford Quasars are among the brightest that happened to align with objects in the universe, far f o r e g r o u n d g a l a x i e s . O n c e University, England. outshining the total starlight of candidates were identified, Hubble’s The data come from the Spitzer their host galaxies. Quasars are sharp view was used to look for Galactic Legacy Infrared Mid-Plane powered by supermassive black gravitational arcs and rings that Survey Extraordinaire (GLIMPSE) holes. To find these rare cases of would be produced by gravitational and Multiband Imaging Photometer galaxy-quasar combinations acting lensing. for Spitzer Galactic (MIPSGAL) as lenses, a team of astronomers surveys. These datasets cover a led by Frederic Courbin selected Quasar host galaxies are hard or narrow, wide strip of the sky 23,000 quasar spectra in the Sloan even impossible to see because the measuring 130° wide and just 2° Digital Sky Survey (SDSS). They central quasar far outshines the tall. From a stargazer’s perspective, looked for the spectral imprint of galaxy. Therefore, it is difficult to a 2° strip is about the width of your galaxies at much greater distances estimate the mass of a host galaxy

The next step for the team is to build a catalogue of “quasar-lenses” that will allow them to determine masses for a statistically significant number of quasar host galaxies and to compare them with galaxies without quasars. With the numerous widefield surveys that will start in the near future or that are already started, hundreds of thousands of quasars will be accessible for looking for lensing effects. www.oneminuteastronomer.com

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Midlands Astronomy Club Magazine

Fledgling stars flicker in the heart of Orion Astronomers using the European Space Agency’s (ESA) Herschel and NASA’s Spitzer space telescopes have detected surprisingly rapid changes in the brightness of embryonic stars within the well -known Orion Nebula. Images from Herschel’s far-infrared instrument and two of Spitzer’s instruments working at shorter wavelengths give scientists a more detailed picture of stars growing in the heart of one of the most famous objects in the night sky.

obscuring dust and reveals these embryonic stars. A star forms when a dense cloud of gas and dust coalesces and then collapses under its own gravity, creating a central warm protostar surrounded by a swirling disk and a larger envelope.

The Orion Nebula is 1,350 light-years from Earth and appears prominently in the winter skies for Northern Hemisphere observers. Sometimes referred to as Orion’s Sword, the nebula lies below the three stars that form the belt of Orion the Hunter, one of the most easily recognized constellations. It is one of the few nebulae visible to the naked eye and is a popular target for amateur astronomers. The nebula contains the nearest site of massive star formation, with intense ultraviolet light from hot young stars causing gas and dust in the region to glow. Inside that dust — hidden at visible wavelengths — is a host of even younger stars still growing in their earliest phase of evolution.

wavelengths. This was combined with archival Spitzer images taken at shorter, midi n f r a r e d wavelengths, which s h ow older, hotter objects. Astronomers were surprised to see the brightness of the young objects varying by more than 20 percent over just these few weeks, since the accretion process should take years or even centuries. They now have to explain why this is happening.

Much of this material will spiral in and collect onto the protostar over hundreds of thousands of years before nuclear fusion is triggered at the core and it becomes a fullyfledged star. Some of the remnant gas and dust in the disk may go on One possibility is that lumpy to form a planetary system — as filaments of gas are funneling from the outer disk towards central happened with our solar system. regions near the star, temporarily A team of astronomers led by warming the inner disk and leading Nicolas Billot of the Institut de it to brighten. Another scenario is Radioastronomie Millimétrique, in that cold material is piling up at the Granada, Spain, used Herschel to inner edge and casting shadows on image the Orion Nebula region the outer disk, causing it to darken once a week for six weeks in the temporarily. In either case, it is late winter and spring last year. clear that the gestation of baby Herschel’s PACS Photodetector stars is anything but a smooth, Array Camera and Spectrometer uniform process. detected cold dust particles in This new combined far- and mid- disks around the youngest “Yet again, Herschel observations infrared image cuts through the p r o t o s t a r s a t f a r - i n f r a r e d surprise us and provide more

Mercury poles give up hints of water ice A Nasa spacecraft has found further tantalising evidence for the existence of water ice at Mercury's poles. Though surface temperatures can soar above 400C, some craters at Mercury's poles are permanently in shadow, turning them into so-called cold traps. Previous work has revealed patches near Mercury's poles that strongly reflect radar - a characteristic of ice. Now, the Messenger probe has shown that these "radar-bright" patches line up precisely with the shadowed craters.

planet. The bright patches were detected by ground-based radio telescopes in the 1990s, but imagery was never available before to see the surface where these radar-bright features are located. The researchers superimposed observations of radar bright patches by the Arecibo Observatory on the latest photos of Mercury's poles taken by the MDIS imag ing ins tr ume nt ab oar d Messenger is only the second Messenger. spacecraft - after Mariner 10 in the 1970s - to have visited the innermost "MDIS images show that all the

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Midlands Astronomy Club Magazine

Enjoy the sights of the Northern lights When conditions are right we get to witness a magical display of light taking place hundreds of kilometres above our heads. The Aurora, or Northern Lights, have been taking place since our world settled down from its creation around 4 billion years ago with the formation of our atmosphere. It is a view most often shared with people further north in the Arctic region, but from time to time, we get lucky down here too.

Above: Baby stars in Orion Nebula. interesting insights into what happens during the very earliest phases of stars and planet formation,” said Göran Pilbratt from ESA. It is only through the unprecedented far-infrared sensitivity and resolution of the Herschel Space Observatory, combined with the shorterwavelength data from Spitzer, that astronomers are able to witness and fully discover the physical processes of star birth. www.astronomy.com

radar-bright features near Mercury's south pole are located in areas of permanent shadow," said Dr Chabot. "Near Mercury's north pole such deposits are also seen only in shadowed regions, results consistent with the water-ice h y p o t h e s is . " H ow e v e r , s h e cautions, this does not constitute proof, and for many craters, icy deposits would need to be covered by a thin layer (10-20cm) of insulating debris in order to remain stable.

at the poles should be rougher than those at low latitudes. "The new data from Messenger... is strengthening the evidence that there is some sort of volatile there, and water-ice seems quite likely." She said information from several instruments on Messenger was currently being analysed in order to answer the ice conundrum: "I think this is a question that we can come to a definitive answer on, as opposed to 'we think it may be this'," the MIT researcher explained.

Maria Zuber who is a coinvestigator on the Messenger mission says "The most interesting interpretation of [the radar observations] is that they were due to water ice. Sulphur had been proposed, there had also been some suggestion it was roughness though there was no reason craters

These findings challenge long-held views about the closest world to the Sun. Messenger was launched in 2004, and entered orbit around its target in March last year. Nasa recently announced that its mission would be extended until 2013. www.bbc.co.uk

Where it starts The Sun, lying almost 150 million km away, is a churning, molten ball of plasma and gas. Hydrogen fusion reactions in the core produce helium, and unleash energy in the process so powerful that energy in the form of light and heat will take 8 minutes and 40 seconds to reach us! Solar Flares and Prominences leap from the Sun's surface and are hurled into space at speeds of hundreds of thousands of miles and hour. Collectively, these are called coronal mass ejections (CME's) this makes up the solar wind. These eruptions go through a peak and trough cycle every 11 years or so. The Sun when heading for a solar maximum, can seen from Earth as an increase in sunspots and detected by spacecraft as an increase in electric flux in space. When any eruption is hurled in our direc tion and s urvives the enormous distance, it hits our protective shield known as the magnetosphere, generated by Earth's natural magnetic field. The magnetosphere is so crucial in protecting the lower layers of our atmosphere that, without it, the atmosphere would be swept away. Think of the magnetosphere as a protective bubble, with 2 small gaps at the north and south magnetic poles. As the particles of the solar wind slam in to it, they slide long magnetic lines to the poles, where they reach our upper layers of atmosphere. It is here where the power of the solar wind strips atoms of some of their electrons, making them electrically charged. The energy released in this process creates, among other wavelengths, visible light. And that is the aurora.

The Storm In the northern hemisphere, they are known as the Aurora Borealis and in the south are known as the Aurora Australis. The excited electrons emit light for anything from tens of minutes to a few days, depending on the intensity of the CME in the first place. This visual part is what we see during a geomagnetic storm. Typically, the latitudes that favour these displays are between 68 and 74 degrees north and south, but a really strong impact swamps the magnetic field and the display moves further south. Ireland averages between 51.5 and 55.5 degrees north, so it takes a strong display to come this far south from the Arctic region. The display can't harm us on the ground, but it can interfere with radio and certain electronic equipment. A massive geomagnetic storm accompanied with an aurora in March 1989 was seen as far south as Texas in the USA and caused an electrical blackout lasting 9 hours over most of the province of Quebec in Canada. Orbiting satellites are also affected when these storms happen. Low altitude spacecraft would normally hibernate for hours at a time to protect their instruments and circuitry. It's not all bad news, of course, when a geomagnetic storm hits. The Light Show We get to see an intense display of ionised gasses glowing in the night sky. Curtains of light in greens, reds and purples dance across the sky, slowly changing shape before your eyes. Sometimes, the display only appears as a glow, other times you can see the pillars of

Above: An aurora in 2011 in Norway, captured by Frank Olsen. light reaching further into space. All this is happening between 100km and 500km above your head. For many observers keeping an eye towards the North is best – when it's not raining! People who live on the West and North coasts have had the best views. You need to get an observing site with as clear a horizon as possible and with as little light pollution. Those living in towns will be at a disadvantage to those living in the country. However, if we get lucky with a much stronger impact, then you won't have to travel far. Remember the colourful displays in 2003? On the nights of October 29th and November 24th 2003, as soon as it grew dark, we could see the aurora. This article's editor remembers watching the November 24th event even before the Sun had fully set in the sky, so intense were the colours. It was so bright and vivid, that ordinary cameras without any corrections or effects were able to capture it. Photography The best means of photographing an aurora is with an SLR camera, digital or film based. The reason is that these all have a Bulb setting or a long-duration exposure setting. Some compact digital cameras also have this setting. To shoot an aurora, your camera needs to be steadied on a tripod or solid surface, aimed towards the sky. The focus setting should be almost at infinity to get the best focus. Then, having set your exposure time for 20 to 30 seconds take your photo. The benefit of digital

Did you know... • The aurora is said to be • • •

continuously occurring between 100km and 500km above the earth’s surface. In Yellowknife Aurora Village in Alaska, it is possible to see the aurora approximately 240 days of the year. The term 'Aurora Borealis' was named by Galileo Galilei. It was the name of the Roman goddess of dawn. Aurora can cause our atmosphere to expand during strong periods of activity, so much so that low-altitude orbiting spacecraft can be gently drawn towards Earth by atmospheric drag.

cameras is that you get to see the results instantly. If it doesn't look right, try a different length of exposure. On an SLR camera, keep your aperture open as wide as possible. Try taking the shot against different objects in the foreground, like Church steeples, old ruins or leafless trees for added effect.

Seanie Morris is the Secretary of the M i d l a n d s Astronomy Club (MAC) having been a member since 1990. Seanie's favourite astronomical interests include meteor watching, deep sky telescope objects and the Moon. www.midlandsastronomy.com

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