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Дата изменения: Fri Jun 2 12:42:06 2006 Дата индексирования: Tue Oct 2 04:12:46 2012 Кодировка: Поисковые слова: jupiter |
From: TerryMoselaol.com Date: 1 June 2006 23:26:51 BDT Subject: Mercury, Visitors to the Beehive, BBQ, Eclipse photos. Hi all, 1. If you have never seen Mercury, the Sun's closest planetary companion, you should start looking over the next few weeks. Conditions are not ideal, but it won't be too hard to find with binoculars, if you know where and when to look. It will be visible in Ireland as an 'evening star' in the first 3 weeks of June, better seen the further South you are. Greatest E elongation of 25* will be on 20 June, but it will be fairly well placed for observing from about June 4 (magnitude -0.6, elongation 18*), through June 22 (magnitude 0.6, elongation 25*). If you have a good clear NW horizon, you should pick it up in binoculars about 30 minutes after sunset. DO NOT start looking for it while the Sun is still above the horizon! With a telescope you might just see some detail on the tiny disc: it's only 5.9" diameter on 4 June, phase 74%, but it increases to 8.5" on 22 June, when the phase has decreased to 35%. 2. The lovely open cluster M44, also known as Praesepe, or The Beehive, in Cancer will have two visitors this month. It lies about halfway between Gemini and Leo, and is a beautiful sight in good binoculars or a rich-field telescope. It is about 70 arcminutes across (just over 2 moon diameters), and contains about 50 stars, the brightest ones being almost 6th magnitude. Saturn has just entered the Southern edge of the cluster, and will pass across that edge over the next 5 days. Saturn is of course much brighter than any of the cluster stars, at magnitude 0.4. But as Saturn draws away from the SE edge of the cluster, Mars closes in from the West. On 6 June it will be only 5 degrees from the cluster and on the evening of 14 June it will have reached its W edge. The most amazing sight awaits us on the next evening, 15 June, when Mars is essentially right in the middle of M44! It doesn't actually occult any of the stars, as it is currently very far from Earth, and hence the disc is quite small - only 4.1" across. It's also a lot fainter than Saturn - magnitude 1.8, just a little brighter than Polaris. Next evening it will be just off the E edge of the cluster. Unfortunately Mars and the Beehive will be quite low in the W sky by the time it gets dark enough to see them properly, so choose a location with a clear W to NW horizon. You can look for Mercury while you are waiting for the sky to darken. On the evening of 14 June it will be 20 degrees to the lower right of Saturn (which will be the easiest object to see in that part of the sky), at an angle of between '3.30' and '4.0' on a clock face. Saturn itself will be just N of West as the sky gets dark enough to see it. Next evening it will have moved about a degree closer to Saturn. Don't confuse it with Pollux (Beta Gem), which will lie about 7 degrees above and left of Mercury, and about 16 degrees right of Saturn, at about the same altitude above the horizon as Saturn. I attach a JPEG chart of their positions at 11 p.m. BST on 15 June. The chart is for Belfast, but it will be close enough for anywhere in Ireland. The azimuth and altitude grid is shown: 270 degrees is due West, 315 degrees is NW. 3. IAA BBQ: Don't forget the social and culinary event of the year: the IAA's midsummer BBQ at Armagh Observatory on Sat 2 June. We start at 3 p.m. with some activities (details later), followed by cooking & eating at about 5 p.m. You bring your own food, drink, eating equipment etc; we provide the heat on which to cook. 4. Eclipse Photos: The June issue of Astronomy Now has superb photos of the total solar eclipse by IAA member David Stewart, and by David Rayner who was also with us on the IFAS eclipse trip to Turkey. Well done. Clear skies, Terry Moseley
Last Revised: 2006 June 2nd
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