The Leonid meteor shower 2020 reaches peak activity on 17 November at 11:00 UT. This peak time is in daylight, but there are also some interesting predictions for dust trail crossings at periods that will be in darkness for UK viewing.
Leonid meteors can typically be seen between 10–20 November. They are fast meteors, associated with the debris stream of comet 55P/Tempel-Tuttle.
The radiant – the point in the sky from which the meteors appear to emanate – is in the curved portion of the Sickle asterism in Leo, the pattern that is meant to represent the Lion’s head (see illustration below).
How to see a Leonid meteor
Leonid meteors are best observed after midnight and technically they should be putting on their best show during the morning of 17 November from 00:00 UT until the onset of dawn, around 05:40 UT.
Find a place away from the light pollution of towns and cities (providing it is safe to do so and is in keeping with COVID-19 restrictions wherever you are) and locate the radiant in the night sky (use a star chart or smartphone astronomy app if need be).
You don’t need a telescope or binoculars to see a meteor shower: in fact these would narrow your field of view. Naked-eye observing is best, but give your eyes about 30 minutes or so to properly dark-adapt and you will be able to see more.
This means no looking at your phone or using a torch, as doing so will ruin your dark adapted vision. If you really need to do either, make sure your phone is set to red light mode (if you’re an iPhone user, find out how to turn your iPhone screen red) or use a red light torch.
If possible, bring a reclining chair to prevent neck ache from spending long periods of time looking up, and wrap up warm. It is winter after all, and meteor observing involves a lot of standing still in open spaces.
How many meteors will I be able to see?
Zenithal Hourly Rate (ZHR) is a useful term to get to know when you’re preparing to observe a meteor shower. It’s a term used to describe meteor shower rates, but is really only for comparison and isn’t intended to represent actual visual rates.
At its peak the 2020 Leonid meteor shower will have a ZHR estimated in the range of 10–20 meteors per hour.
However, ZHR assumes a shower’s radiant is directly overhead and the observer is able to take advantage of a clear, dark sky with no visual obstructions. The actual number of meteors that can be seen should be lower than the quoted ZHR.
A watch on the morning of 18 November should still produce results, but is further from the predicted ZHR peak of 11:00 UT than the morning session on the 17 November.
An added bonus is that this year’s new Moon is out of the way for the peak period.
Although there’s a prediction of enhanced activity from 06:50 UT until 08:13 UT on the morning of 17 November, it’s expected that this will consist mostly of faint meteor trails. It’s also when the sky will be bright with morning twilight from the UK.
A second period of enhancement may occur during darkness in the early morning of 18 November at 00:58 UT.
However, it’s not expected that these predictions are going to produce significant rate increases as the trails which are responsible for them will have spread over time and will have become sparse.
Pete Lawrence is an experienced meteor shower observer and a co-host of The Sky at Night.