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Astronomy Know How Helping you See the Night Sky - Newsletter No. 35 September 2009 |
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In this issue: |
| September's Highlights September brings us longer nights and cooler nights as well, so it makes sense to wrap up if you are going outside to do any lengthy observing. The autumn equinox is on the 22nd September at 21:19 UT (the same as Greenwich Meantime). This is when the Sun crosses the celestial equator and moves to the southern part of the celestial sphere from the northern, where it has resided for the summer months. This means that after this date, the night will get longer and the days shorter. The moon is full on the 4th of the month and 'new' on the the 18th. So any time between or after these two dates is good for observing our closest neighbour in space. Full Moon is not the best time for lunar observing as there are no shadows on the surface and so features are hard to distinguish. Even slight shadows help features on the moon stand out. The Summer Triangle of the stars Deneb, Altair and Vega is now high in the south after dark and move steadily westward as the night goes on. These stars are found in the constellations of Cygnus (Deneb), Aquila (Altair) and Lyra (Vega), three summer constellations. The triangle itself was named by our very own Sir Patrick Moore and has now moved into common usage. The main constellation of autumn is Pegasus the Winged Horse. This group of stars rides high in the night sky in the south around midnight. The horse in fact hangs upside down from our view point in the northern hemisphere with its head on the western side of the constellation. The most recognisable asterism or part of the constellation is the 'great square', although it does not contain any particularly bright stars. The stars of the Square are separated by roughly the same with as your fist held at arms length. You can count the number of stars in the Square to give you an estimate of the quality of the viewing conditions. If you can count five or more with the naked eye, conditions are fairly good, but if you can only count less than this number then either the sky conditions are poor or you are probably suffering for the effects of light pollution. |
| Magnificent Jupiter Jupiter is now easily visible in the late evening sky as the brightest 'star' above the southern horizon. If you have a small telescope, then turn it to this beacon in the night sky. You won't be disappointed. Even with a modest telescope and a medium power eyepiece, you should be able to detect a couple of belts in the planets swirling atmosphere. To help you get your bearings, Jupiter now resides in the constellation of Capricornus the 'Sea Goat' (whatever a 'Sea Goat' is!) and it is given an even brighter marker on the evenings of the 2nd September, when the Moon is very close the planet (from our point of view) and again on the 29th of the month. You should notice that Jupiter has a slightly flattened disc, otherwise called 'oblate', due to its rapid rotation. It spins on its axis in 10.5 hours, a very short day for a very big planet! Also, keep an eye open for the 'Great Red Spot'. Well it's not particularly red unless you have a large telescope with which to view it and you won't necessarily see it every time you look as it may be around the back of the planet. This 'spot' is a huge storm the size of planet Earth that has been raging in Jupiter's atmosphere for the last few hundred years, with wind speeds of over 400 miles an hour! |
| The Moon and M35 On the evening of 12th September, the waning crescent Moon, will make a close pass of the open star cluster Messier 35 or M35 as it is known. This will act as a good marker to this lovely cluster of stars if you have never seen it before and in itself is interesting as the cluster and the Moon have a similar apparent diameter. The best way to observe it is with either binoculars or a telescope with a low power. The closest approach is at 23:00 UT (midnight BST) when the centre of the cluster and the centre of the Moon will be only around 0.5-degrees apart. As the Moon and the cluster are both 0.5 degrees across, the Moon will appear to skim the edge of the cluster. Hopefully this will give you a good sense of scale, something that is not always easy to determine in the night sky. The brightness of the Moon will drown out the fainter stars of the cluster, but remember just how large M35 is on the sky, when you have the Moon for comparison! |
| Finding the planet Uranus Not many people have spotted the planet Uranus as it is quite faint, only just on the edge of naked eye detectability from a dark sky site. So you'll need binoculars at least if you have a hope of finding it. The planet lies not too far from Jupiter, to the east and slightly north of the giant planet and almost directly under the Square of Pegasus and the 'Circlet' asterism of Pisces the Fish. The best time to see it is on the night of 17th when it reaches 'opposition', that is it lies directly opposite the Sun in the sky from our point of view. But of course you can see it well at any time during the rest of the month. Uranus was discovered by William Herschel from his garden in Bath in 1781 using his home made telescope. It is not a particularly interesting body to observe as it will at best appear as a small pale greenish coloured disc, but it is worth remembering just how far away this cold remote planet is at a mean distance of 1,770,000,000 miles and is the third largest planet in the solar system. The best way to track it down is to use a star chart or software and 'hop' to it using recognisable patterns of stars. You will know you've found it when you see a star that is noticeably 'larger' than the rest and has a bluish/greenish colour. Using a large amateur telescope it should be possible to detect some of the moons of Uranus. Ariel, Umbriel, Titania, Miranda and Oberon should all be detectable in apertures of at least 14-inches. Uranus has 21 known moons and a very faint ring system discovered by the Voyager probe. |
| Deep sky Delights in September I can't mention deep sky objects that are worth observing in September, without first mentioning the Andromeda Galaxy. More than any other deep sky object people ask me to tell them how to find this beautiful object. So here goes... Unless you are blessed with a really dark sky, the best way to find M31 as the Andromeda Galaxy is known, is to use a pair of 7x50 or 10x50 binoculars. There are a couple of ways of tracking it down. Using the top left hand star of the Square of Pegasus, which is in actual fact the star Alpha Andromedae, move slightly up and to the left until you find the next brightest star. This is Delta Andromedae. Do the same thing again, this time moving more steeply upward and you should then find a brightish star which is Beta Andromedae otherwise known as Mirach. Now head up and to the right of Mirach and find a slightly fainter star Mu Andromedae and move the same distance in the same direction, where you should find Nu Andromedae and the faint smudge of light just to the right of Nu is the Andromeda Galaxy. It's not the easiest object in the sky to find, but well worth the effort. It is accompanied by two other smaller, fainter galaxies M32 and M110. See if you can spot these as well. While you are in Andromeda, go back to the star Mirach and head in the opposite direction to M31 to find M33 the Triangulum Galaxy. This is quite faint and will need binoculars to be found. It is a large face on spiral galaxy with a low surface brightness but binoculars should show some faint structure if you are not plagued by light pollution or a bright Moon. More next month... |
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Here are some links to some other recent news stories that I thought you would find interesting... New Theory on How Spiral Galaxies Got Their Arms The old, epicycle one seems to be flawed. more... X-ray telescope to shed light on dark energy 2012 will see the start of the search for black holes and dark matter in an attempt to answer why the expansion of the universe is accelerating instead of slowing down. more... Mystery storm clouds on Saturn's largest moon appear Caltech researchers find the first evidence of a methane storm over Titan's equatorial zone, where dry channels were possibly carved by rain. more... Space telescope captures ancient light from Big Bang The European Space Agency's Planck telescope, launched in May, has begun to look at light and radiation left over from the Big Bang. more... Scots aid discovery of new planet The new planet - described as 'bloated' and 'as dense as expanded polystyrene' - has been found to orbit its star in the 'wrong' direction, using software developed by astronomers at the University of St Andrews. more... |
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Do you want to learn more about the night sky and how
to use telescopes and binoculars to see it better?.. My online course gives you all the essential information to be a good astronomer, without lots of jargon or difficult maths. You'll get loads of free bonuses and it also has videos and animations to help make the explanations clear and concise. So if you want to know what Sir Patrick wished for... ...please take a look at my eCourse called 'Basic Astronomy with a Telescope'. It's what Sir Patrick wished he'd had when he started out in astronomy! |
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Are you interested in Imaging? You can learn how to take stunning images of the night sky with your digital slr camera that will amaze your friends and family with the eBook DSLR Astrophotography - A Beginners Guide which I co-wrote with my friend Jon Walton... |
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