Total Lunar Eclipse, 2001 The 15th annual guide to astronomical phenomena visible from Ireland during the year ahead (naked-eye, binocular and beyond) By Liam Smyth and John O’Neill Published by the Irish Astronomical Society € 5 P.O. Box 2547, Dublin 14. e-mail: [email protected] www.irishastrosoc.org Page 1 Foreword Contents 3 Your Night Sky Primer We send greetings to all fellow astronomers and welcome them to this, the fifteenth edition of Sky- 5 Sky Diary 2007 High. 9 The Planets in 2007 This year, while retaining the colour covers, we 11 Eclipses in 2007 have again increased the number of pages. We 12 Comets in 2007 thank the following contributors for their articles: Patricia Carroll, John Flannery and 13 Meteors Showers in 2007 James O’Connor. 15 Asteroids in 2007 16 Location, Location, Location! The times of sunrise etc. are from SUNRISE. EXE by J.O’Neill. The asteroid and Comet Tuttle 18 Variable Stars in 2007 charts are from Guide 8. The M33 chart is from 19 The Year in Space Megastar 5. 21 Observing the Satellites of Jupiter We are always glad to hear what you liked, or 22 Some Favourite Double Stars what you would like to have included in Sky-High. If we have slipped up on any matter of fact, let us 25 Asteroid Charts know. We can put a correction in future issues. And 27 Misc. if you have any problem with understanding the contents or would like more information on any 28 Gallery topic, feel free to contact us at the Society e-mail address [email protected]. 2007 marks the 70th anniversary of IAS, see Up-to-date news of IAS activities and links to Website for our special meeting to mark the occa- sites of interest on the internet can be found on our sion. It is also ten years since Comet Hale-Bopp own website at www.irishastrosoc.org. made its majestic appearance, lets hope for an- other such comet in the not too distant future. Also on the Society Website is Sky and Gallery which highlights some celestial events featured in Wishing you clear skies for 2007, Sky-High. Also featured will be unpredictable John O'Neill and Liam Smyth events such as bright comets and bright superno- vae. Sky-High 2007 (2nd printing) © IAS, 2006 The Irish Astronomical Society Founded in 1937, the Irish Astronomical Society The Society also has a well stocked library of caters for those of all ages and interests in astron- books and journals that members can borrow as omy and space. well as access to a number of telescopes that can be loaned for a period. You don’t have to be an expert to be part of our dynamic club. Many of our members are taking their A number of IAS members have made their own first steps in the hobby and you are sure to receive telescope while others possess telescopes ranging in friendly advice from some of the more experienced size up to a 70 cm behemoth! Many are now experi- amateur astronomers in our group. menting too with the latest technologies to hit the amateur community such as Web Cams. Activities include monthly meetings, receiving our bi-monthly magazine Orbit and this annual Sky- If you are considering purchasing a telescope High, observing groups, e-mail alert notices of tran- then we’ll point you in the right direction before sient astronomical phenomena such as aurora, and you take the plunge and part with your hard-earned outings to places of astronomical interest. cash. Members have joined expeditions to observe sev- The Dublin Sidewalk Astronomers hold public eral total solar eclipses world wide as well as catch- star parties at regular intervals usually in ing the wonders of the night sky from home. Sandymount, Dublin (see IAS website for details). Page 2 Your Night Sky Primer As with any hobby, astronomy seems to have it's stellation charts with many interesting celestial ob- own set of terminology designed to confuse. How- jects labelled. ever, with a little patience you'll soon pick up the jargon and be well on the way to knowing your way For more detailed studies, especially with bin- around the sky. oculars or a small telescope you will need a more detailed map showing all stars to at least sixth mag- The revolving heavens nitude. A recent entry is Atlas of the Night Sky We all know the Heavens don't revolve, it is the published by Collins for about €30. This shows stars other way round, the Earth rotates on its axis. But to magnitude 7.5 and the positions of many Deep it looks otherwise and it is easier to describe things Sky Objects. as we see them for our immediate purpose. The fact that the Earth turns on its axis about every 24 An idea of size or scale hours causes the Sun to rise in the east and set in If you have seen a picture of a total eclipse of the west, and it is due south at noon. A similar the Sun you will have noticed that the black disk of situation applies to all the other heavenly bodies the Moon just about covers the bright disk of The except that since they appear to move relative to Sun. If you were to suspend a one Euro coin about the Sun they are not south every day at noon. two and a half metres in front of your eye, it would just about cover the Moon's disk. The stars appear to drift west in such a way that any particular star is due south four minutes earlier The Sun is nearly 1.4 million km in diameter, the each day or night. If you multiply four minutes by Moon is 3476 km and the one Euro coin is just over 365 you get something close to 24 hours. So if a star two centimetres in size. Yet they appear nearly is south at eight o'clock tonight, it will be south equal. This is because they all seem to take up the four minutes earlier tomorrow, and two hours ear- same amount of the space in front of our eyes. We lier in a month. In six months it will be south at may say they have the same angular diameter. In about eight in the morning. In a year it will again this case it is about half a degree (½°). be south at eight in the evening. It follows that we see different constellations in different seasons, Degrees are further divided into 60 arcminutes but over a year, we see all that portion of the heav- (60') with each arcminute made up of 60 arc- ens that can be seen from Ireland. seconds (60"). The scale allows us to measure an- gles in the sky or apparent size of a celestial ob- Star maps ject. For example, the Full Moon measures an aver- You will need at least one star map. This could age of half a degree, or 30 arcminutes, in diameter. be a set of monthly charts such as are included in many books on astronomy. Phillips' Planisphere is Your closed fist held at arms length is about ten very useful. It comes in various sizes at equivalent degrees (10°). Your stretched out hand, i.e. from cost. It allows you to show the constellations visible the tip of your thumb to the tip of your little finger, at any time of the night, any time in the year. is about twenty degrees. Between four and five out- stretched hands or twice as many closed fists will You could get away with using the monthly take you from the horizon to zenith. If you charts published in newspapers but there are a cou- know the Plough you will find that its overall length ple of drawbacks. Each chart is correct for only one is rather more than one outstretched hand, it is al- time on a given night, say 10 p.m. If you are observ- most 25 degrees. ing two hours later you would need the following month's chart. These charts also show the planets A “handy” way to visible for a particular month, so they can be con- measure scale in the sky. fusing unless you tippex them out. When learning The tip of your little fin- the constellations check first from the monthly ger at arm’s length covers notes if there is a bright planet in the area. ½°; i.e. the apparent width of the Full Moon. A Once you can find the constellations you will en- good demonstration of joy learning more about them. the illusion that the Moon looks big is that it would A delightful pocket-sized book is Stars - part of take ten Full Moon’s side- the Collins Gem series that is available for about by-side to span the gap seven Euro in any bookstore. Don't let its diminutive between the two “pointer” stars in the appearance mislead you; it's packed with informa- Plough — a distance of tion and the core of the book features a set of con- just 5°! Page 3 rectly through the North Celestial Pole (NCP) to Some familiarity with angular measure is neces- the zenith and then continues on down to the sary to find your way easily about the sky. southern point of the horizon. The NCP is less than one degree from Polaris, the Pole Star. Positioning in the sky Starting at any landmark and going right around Venus and Mercury show phases like the Moon.