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Astronomy Know How Helping you See the Night Sky - Newsletter No. 42 April 2010 |
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In this issue: |
| Welcome Thanks for subscribing to this my FREE! monthly newsletter. I hope that you enjoy it. Here you'll find information about what you can see in the night sky over the coming month and some tips on how to observe some of the things mentioned. I hope that you find it useful and please let me know what you think and let me have any ideas as to what you might like to see in it. I would like this to be as much your newsletter as it is mine... I wish you clear skies, Ninian |
| April's Highlights We are now into Spring and with it a great time for exploring objects in both the Solar System and out in deep space. We have some interesting views of the inner planets Mercury and Venus this month and some visual treats from Mars and Saturn. More below... The Virginid meteor shower is due to put in an appearance this month on the 12th. However, this is not a'big' shower by any means with a Zenithal Hourly Rate - that is the average number of meteors you could expect to see if the shower were overhead in completely dark skies(!) - of only 5 meteors per hour. THe good news is that the Moon is out of the way, so although this is a weak shower, keep an eye out for long slow meteors appearing to emanate from the constellation of Virgo. We also have the April Lyrid meteors on the 22nd. Although this is a much stronger shower, unfortunately, we have a first quarter Moon that will likely drown out all but the brightest meteors until it sets 02:00UT on the 23rd. This shower has a predicted ZHR (Zenithal Hourly Rate) of 10 meteors per hour. If you are interested in variable stars, then there are two minima of Beta Persei, otherwise known as Algol, this month. Algol is supposed to represent the eye of the Gorgon, the head of whom Perseus cut off with the aid of the mirror-like surface of his shield. Legend has it, that if you looked at the Gorgon directly, you would turn to stone. Fortunately, this has never been known to happen to observers of Algol! The first minimum is on the 15th 01:30UT and the second is on the 17th at 22:20UT. Don't forget to add an hour for those of us on BST. The Minor planet 2Pallas reaches opposition on 30th April. If you would like to try and spot it, you'll need binoculars or a small telescope as it is at magnitude 8.7 and a star chart to find it in the region of Serpens Caput and fairly close to the constellation of Corona Borealis. |
| Spotting Mercury We have a few good opportunities to spot Mercury this month. This elusive little planet is always hard to find, so see if you can locate it this month using some of the tips below. Probably the best time is just after sunset on the 1st of the month. Mercury is at its brightest and you can find it by first locating bright Venus and the little planet Mercury can be found just to the right (west) of Venus. On the 4th April the separation between Mercury and Venus is at its smallest. These two planets will appear separated by just 3-degrees or six times the diameter of the full Moon. You should be able to locate the pair if you have a clear horizon just after sunset low down in the west. Mercury reaches is greatest elongation, that is the furthest that it can appear from the Sun on the 8th of the month. It will now be 19-degrees from the Sun, but you'll still have to be quick to spot it, as you only have around an hour and a half before it disappears into the murk itself. Venus is still quite close by to help you. |
| Mars and the Beehive Lets face it, Mars can be very disappointing to amateur astronomers. It spends such a short time at opposition where we can see it well and this only happen every couple of years. The Red Planet is now racing away from us as our orbits diverge... It is now a small 9 arc-seconds across and getting smaller so features on the disc will be hard to spot with all but the largest of amateur telescopes as the month progresses. By the end of the month it will be only 7 arc-seconds across. It is now only 91% illuminated and shows a 'gibbous' phase. However, it can still be a pleasing sight and presents a nice photo-opportunity in mid-month. The planet is moving steadily eastward through the constellation of Cancer the Crab and will pass close by the open star cluster M44 otherwise known as the Beehive Cluster on the night of the 17th. It will be just north of the cluster then and should look very photogenic. If you plan to try and take a picture and are using just a camera and tripod, then use a wide angle 28mm lens to reduce 'star trails'. If you can 'guide' your camera then you could use a short telephoto lens of say 80mm. The suggestion here is to take pictures over several nights to help increase your chances of getting a good shot and a clear night! Good luck. |
| The Rocking Moon No, I'm not talking about Moon rocks, but a phenomena known as libration. The Moon, although it always shows us the same face, in fact shows us a little more than just 50% of its surface due to the fact the it wobbles from side to side in its orbit. So we can around 58% of its surface over the course of some time. On the 28th April the north-eastern limb of the Moon will be turned towards us more than usual, so that we will get a chance to see Mare Humboldtianum or the Humboldt Sea. It will appear as a dark patch on the lunar surface almost at the edge of the disc and very foreshortened. You may need a Moon map to help you find it. You can find a good moon map here (UK) or a variety of moon maps here (USA) Also, while you are looking around the corner of the Moon, see if you can spot Mare Marginis the Marginal Sea. Find Mare Crisium known as the Sea of Crisis and keep going towards the edge of the disc as you did with Humboldt. This too, will be very foreshortened as we don't often get any opportunity to see this part of the lunar rim. |
| Deep Sky Highlights of April Spring is the season of galaxy hunting and here I'll point out one or two of the spectaculars sights that you can see with only modest equipment... Your galaxy quest could start in Leo the Lion. There are two sets of galaxies here that should be visible on a Moonless night and with clear transparent skies even in 7x50 or 10x50 binoculars. Firstly M95 and M96 can be found just below an imaginary line drawn between the stars Regulus and Chertan marking the 'belly' of the lion. These should appear as faint 'smudges' of light in binoculars and small telescopes and in the same low power field of view. Next there is the 'Leo Triplet'. This triangle of galaxies are further to the east the M95 and M96 but lay on the same line below the Lion, just to the south and east of Chertan. Again, these should appear as faint 'fuzzy stars' and all in the same low power field. These are labelled M65, M66 and NGC3628. With the latter being the eastern most of the group. Galaxies can be a little disappointing when viewed through a small telescope as we are used to seeing fantastic images of these objects taken through such instruments as the Hubble Space Telescope, but do remember that M66 for example is some 35 million light years away! The fact that we can see these objects at all with modest instruments is arguably, astounding. If you still have an appetite for galaxies, then the area east of Leo, including the constellations of Virgo to the south and Coma Berenices is known as the 'Realm of the Galaxies'. This region is a veritable feast for the deep sky hunter and contains (among others), the galaxies M60, M58 and M87. There are too many galaxies here to allow me the room to give detailed descriptions of these objects or where to find them, so I would recommend a good star chart or book to help you track them down. So, with that in mind, I can recommend 'Galaxies and How to Observe Them' by Wolfgang Steinicke. You can get it here (UK) or here (USA) If galaxies aren't your thing, then there is a lovely globular cluster that is worth a visit in Coma Berenices. This is M53 and is easily visible in 7x50 or 10x50 binoculars. You can find it about one degree (two Moon diameters) to the north east of the star Alpha Comae. Again a star chart should help you find it. |
| Other News If you frequent YouTube, then you can find a short video that I have put up there called 'Understanding The Night Sky', which explains how the night sky works, inasmuch as it will show you how what you can see in the night sky is governed by where you are on planet Earth and also the time of year. It also describes how the constellations have come to be formed. Do please take a look and leave a comment - feedback is always welcome. You can find it here... I've finally entered the 21st Century and have joined Twitter! If you would like to follow me on this particular micro-blogging site then please drop by www.twitter.com/astroknowhow I mentioned last month that we are updating the AstronomyKnwoHow web site. This is still ongoing and we are hoping to complete it in the next few weeks. It will have loads more information and a fresh new look that we hope you'll like and find easier to navigate around. So do keep checking back regularly... I'm off to sunny (I hope) Spain for a few days to help complete the installation of the Griffon Educational Observatory down in Andalucia. This is an excellent facility under beautiful dark and transparent skies. It will be welcoming guests later in the year and I will report more about this on the web site when I get back and in the next Newsletter. So, if you fancy a few days (or should that be nights?) of astronomy under skies that town dwellers would murder for, keep coming back to the site, as I'll get the details up there soon. |
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Here are some links to some other recent news stories that I thought you would find interesting... Hubble telescope to tackle the big questions Astronomers will study 250,000 distant galaxies for clues to origins of the universe more... Hope and a telescope enthrall Gaza stargazers "This is something beautiful," said Abdullah Majaideh, 14, after gazing heavenward. "I never expected to look into the telescope and see the outside world." more... Discovery of earliest known black holes announced by astronomers Astronomers have discovered what appear to be two of the earliest and most primitive supermassive black holes known. more... Star set to collide with solar system Gliese 710, which can be seen in small telescopes, has our solar system clearly in its sights. more... How Jupiter changes its spots Thermal imaging reveals the meteorological mechanics behind the solar system's strongest storm 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?.. You can find all the information that you really need in my online course. It 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 Moore 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... |
| To contact us You can write to: Ninian Boyle c/o B2 The Wren Centre, Westbourne Road Emsworth, Hants, England PO10 7SU or Telephone me on +44(0)208-144-1091 or contact me by email You are receiving this newsletter because you filled in a form on the Astronomy Know How Website on {!signdate long} but you can change your email address by which we contact you, or unsubscribe if you no longer want the newsletter or think you have been subscribed incorrectly by scrolling down and use the link below |