The Leonid Meteors 2007
Unfortunately it isn't possible to have a "once in a lifetime" chance every year. It has been calculated that there will be no big meteor storm during this year's Leonid shower. However, if you do want to observe, then the best nights to aim for are probably the night of the annual "nodal crossing peak" (see the IMO Meteor Shower Calendar) when the Earth passes through the orbital plane of Comet 55P/Tempel-Tuttle, and the night after when there will be (low level) outburst activity. The first peak (annual nodal crossing) falls in the early hours of November 18th (UT or GMT). The next night, with outburst activity, falls on the night of the 18th (or early hours of the 19th), for those at European to Asian longitudes. At other longitudes, you can still concentrate on the night(s) closest to these; you should still be able to see some Leonids, given a clear, dark sky.
Some years ago, Esko Lyytinen found that the trail created at the comet's 1932 return (i.e. 2 revolutions ago) - the same trail that produced the 2006 outburst - will also be encountered by the Earth in 2007. Although the level is expected to be below that of the 2006 outburst (which itself was well below storm level), it should still be detectable above the background. Moreover, Jeremie Vaubaillon's calculations show that material from the 8-revolution trail created around the comet's 1733 return can reach the Earth, even though the central, densest part of this trail is well away from Earth.
McNaught-Asher theory (which follows the techniques pioneered by Kondrat'eva and Reznikov) gives the following timings for the 2-rev and 8-rev trail encounters in 2007:
(we didn't study the 2007 Leonids in detail; the above numbers were just to check we agree with Lyytinen and Vaubaillon, and the calculations are indeed consistent).
2-rev Nov 18, 22:40 UT
8-rev, 1st encounter Nov 18, 19:45 UT Distant encounter, timing imprecise 8-rev, 2nd encounter Nov 19, 00:10 UT Distant encounter, timing imprecise
For further information on the 2007 Leonids, useful webpages include the following:
Peter Jenniskens / Leonid MAC
Leonid meteors are best seen in the second half of the night (exactly how many potential observing hours you get depends on your latitude). This year on November 18th and 19th, the Moon will be just after first quarter, which is quite good since it will have set by the time the Leonid radiant is reaching a reasonable altitude.
Armagh Observatory main Leonid page
Last Revised: 2007 November 7th
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