The Leonid Meteors

Predicting the most spectacular meteor storms is now a remarkably exact science, with some excellent Leonid displays happening in recent years, for observers in the right parts of the world. These predictions involve the accurate modelling of dust trails within the Leonid stream.

Leonids in 2010

Nothing spectacular is expected from the Leonids in 2010. Indeed, attention is turning instead to major outbursts in other showers, such as the 2011 Draconids.

For the 2010 Leonids, it is possible (see links below) that the peak ZHR (Zenithal Hourly Rate, the rate of meteors seen in idealised observing conditions) could reach as high as 20, which would be marginally more than in standard Leonid years. This peak will be around 15:00 UT on the 17th of November (Pacific longitudes best) with the traditional peak being around 21:00 UT that day (central to east Asian longitudes best).

Links:

IMO Meteor Shower Calendar
Maslov: Leonids 2010: prediction of activity
Maslov: Leonids 2009-2010, including Leonids 2010 overview
Maslov: parameters of Leonid trail encounters 2001-2010

Leonids in 2009

Although the 2009 shower will not produce the storm level activity of the Leonids some years ago, observers in the right part of the world should see some nice outburst level activity. This will be due to material released by the Leonid parent comet, 55P/Tempel-Tuttle, at various past returns, especially those in 1466 (16 revolutions ago) and 1533 (14 revolutions ago).

Here are some 2009 Leonid results we calculated with dust trail theory, i.e. following techniques pioneered by Kondrat'eva and Reznikov:

Trail Delta a_0 rE-rD AU f_M Time

14-rev +0.136 -0.0005 -0.09 Nov 17, 21:15 UT

16-rev +0.105 +0.0011 0.10 Nov 17, 21:20 UT

16-rev +0.106 +0.0009 -0.04 Nov 17, 22:00 UT

- notation explained in Mc Naught and Asher's paper. A fuller list of trail encounters in 2009 is provided by Mikhail Maslov's comprehensive study.

In fact, the above trail encounter data should not be interpreted as having the same accuracy as data for very young trails, because these older trails have had more time for the meteoroids in them to become more scattered or disrupted. But the independent calculations of various researchers have confirmed that both these trails ARE encountered by the Earth in the late UT/GMT hours of Nov 17 (maybe extending to the very start of Nov 18 depending on duration). See especially the results of Jeremie Vaubaillon's computer models.

Mid-Asia is best placed to see the resulting outburst activity. Prakash Atreya, formerly of Armagh Observatory, is organising an international Leonid observation campaign in Nepal.

As the lunar phase - virtually new - is excellent for the 2009 Leonids, there should at least be a few Leonids to see wherever (clear and dark) you are, on nights near Nov 17. Leonid meteors are best seen in the second half of the night (exactly how many potential observing hours you get depends on your latitude).