From: TerryMoselat

Subject: Twitter, Lecture, Comet to hit Mars? N-E Comet, IAA@Dungannon, COSMOS, more

Date: 6 March 2013 01:46:10 GMT

Hi all,


1. TWITTER. You can now follow me on twitter: at signterrymoseley2


2.  IAA LECTURE: The next IAA public lecture will be on Wednesday 6 March, at 7.30 p. m. It will be given by Professor Tom Ray, of the Dublin Institute of Advanced Studies (DIAS). The title is "From Pebbles to Planets: Our changing ideas of how the Solar System formed".

    Prof Ray is a leading researcher in many areas of astronomy and astrophysics, and is Co-Principal Investigator of the Mid-Infrared Instrument (MIRI), one of the four main instruments on board the James Webb Space Telescope, the replacement for the HST.

    Tom studied at Trinity College Dublin before working at Jodrell Bank, the University of Manchester, the University of Sussex and the Max Planck Institute for Astronomy in Heidelberg. He is currently Professor of Astrophysics at the Dublin Institute for Advanced Studies, specialising in star formation.

   Tom has given several lectures to the IAA, and is an excellent and entertaining speaker, so you shouldn't miss this one.

   Admission is free, including light refreshments, and all are welcome.

This lecture will as usual be in the Bell Lecture theatre, Physics building, main QUB Campus.


3. Update: POSSIBLE COMET IMPACT ON MARS: 19 October 2014

In October 2014, Comet C/2013 A1 (Siding Spring) Discovered by Rob McNaught, will pass extremely close to Mars. There is still some uncertainty in the orbit, so there is a very slight chance that it could hit the planet! NASA estimates that the chance of a collision is about 1 in 600. If it did, it would be an impact of billions of Megatons!

    From Earth the comet and Mars will be less than a minute of arc from each other, which will look quite nice in a telescope (but hard to image as the comet will be about magnitude 8.5 and Mars will be much brighter).

   Mars will be mag +0.9, diameter 5.75". The elongation from the Sun will be 59 degrees, but its declination will be almost 25 deg south, so it will be almost impossible to see from here, very low down in twilight. One would need to go South to the latitude of the Canaries, or further South, and either East or West for the best longitude. But if an impact is likely, it would be worth going anywhere in the world to guarantee seeing it!

   We don't know the exact time of closest approach yet, but if the comet is on inward trajectory, any possible impact would probably be on far side of Mars as seen from Earth. Depending on just when and where the impact (IF one occurs) happens, we could have to wait up to just over 12 hours for the impact site to rotate into view from Earth. However, as with the Shoemaker-Levy 9 impacts on Jupiter, if it occurs just behind the limb of Mars, we would see the impact plume shooting up into the sky.

    And there is also a very remote possibility that it could impact one of the Martian Moons, Phobos (diameter 27 x 22 x 18 km) or Deimos (diameter 15 x 12 x 10 km), which orbit at distances of 9380 km and 23460 km from Mars. Such a collision would itself be a multi multi megaton event!




   Comet Pan-STARRS (C/2011 L4) was discovered in 2011 by the Panoramic Survey Telescope & Rapid Response System a 1.8-m telescope in Hawaii that is used to watch for objects that might pose a danger to Earth.  In early March, the comet will pass about 90 million miles from Earth, briefly dipping inside the orbit of Mercury.

   Since it will be quite close to the Sun it may become visible to the unaided eye; maybe about as bright as the stars of the Plough.  However, the brightness of a new comet is always a bit unpredictable. When such comets occasionally fall towards the Sun we don't know how they will react to the Solar heat and light.  This Comet is probably on its first visit to the inner Solar System, so it could either disintegrate without getting too bright, but it could also throw off a lot of gas and dust and become a nice sight in our night sky.

    Because it will go close to the Sun it could be quite active, but could still be difficult to see, because when at its best it will appear very close to the Sun, only observable in twilight.

  The best dates to look may be March 12 and 13 when it appears in the western twilight not far from the crescent Moon.  A comet and the crescent Moon in the twilight glow is a rare sight.  The head of the comet may well be visible to the naked eye, but a good view of the tail may require use of binoculars or a small telescope.

The following site gives good viewing information for our latitude:

And this is an excellent guide to observing comets in general:


5.  IAA at St Patrick's Academy, Dungannon, 8 March. There will be another public astronomy evening on Friday 8 March, at the school at 7.30 p.m. As well as the school's own 14" Celestron, once again we'll have a selection of our own powerful telescopes and binoculars for viewing the night sky, an exhibition, short astronomy and space films, a selection of meteorites (rocks from space) which you can actually hold, and of course the Stardome mobile planetarium just in case of bad weather. And you'll have a chance to meet our own 'Ulsternaut', Derek Heatly from Groomsport, who is booked to fly into space with Virgin Galactic.

There will be several shows (admission charge) in the Stardome during the evening, and these MUST be booked in advance by ringing the school at

 37 Killymeal Rd, Dungannon, County Tyrone BT71 6DS T. 028 8772 7400

  The highlight will be a great view of giant Jupiter, the largest planet in the Solar System, with its four large Moons all beautifully laid out, two on either side of the planet. Observing is of course weather dependant.

 See also: These are always very popular events, so book early.

6.  Postponed: The IAA Public Astronomy Event at Glenarm Castle scheduled for 18 March has been postponed until later in the year.


7. COSMOS 2013: The next COSMOS star party will be held at Tullamore on 12-14 April. Speakers so far confirmed: Sara Beck of the American Association of Variable Star Observers from Boston, USA; Prof. Ian Morison, former Gresham Professor of Astronomy, Gresham College, London; Simon Jeffrey, Research Astronomer at Armagh Observatory; Declan Molloy, Midlands Astronomy Club; Simon Todd, renowned Irish astrophotographer; Dave McDonald, IFAS Chairperson and renowned asteroid hunter. And more still to be announced!




9. TWITTER: Follow the IAA on Twitter:  at signIaaAstro

10. BBC THINGS TO DO WEBSITE: See the forthcoming IAA events on Look under 'Countryfile'.


11. JOINING the IRISH ASTRONOMICAL ASSOCIATION is easy: This link downloads a Word document to join the IAA. If you are a UK taxpayer, please tick the 'gift-aid' box, as that enables us to reclaim the standard rate of tax on your subscription, at no cost to you.  See also


Clear skies,

Terry Moseley

mob: (0044) (0) 7979 300842

Twitter: at signterrymoseley2