Leonid meteor shower: A beginner’s guide

17 Nov 2015

One of the last meteor showers of the year is almost upon us, with the Leonids lighting up the skies tonight (17 November), but what are we to expect?

The Leonid meteor shower relates to the lion constellation, Leo, with meteors piling out from that point in the skies.

Expected to peak over China, Thailand and Japan, Europe should get quite a show, too, with Astronomy Ireland conducting a nationwide meteor count tonight and over the coming days.

That’s because the Leonids rain for around four days, peaking in the middle, with that point coming tonight around midnight.

We love a bit of Leo

The Leonids have been observed by humanity for centuries and are the result of Earth passing through a cloud of dust left behind by Comet Tempel-Tuttle.

As our planet moves through this cloud, the particles fall into our atmosphere and burn up, creating spectacular streaks of light in the sky, known as meteors or shooting stars.

This shower is named after the constellation Leo, from which the meteors appear to come from in the sky.

Go away moon

But, as NASA explains, the moon is not the meteor watcher’s friend. “Light reflecting off a bright moon can be just as detrimental to good meteor viewing as those bright lights of the big city,” according to the space agency.

“There is nothing you can do except howl at the moon, so you’ll have to put up with it or wait until the next favourable shower.”

So, from 9pm, people in Ireland should start to see activity rise, with the moon’s setting time of 10pm letting those outside of the cities see even clearer in a pitch black sky.

Go away clouds

Of course, it is not just the moon to be wary of, with clouds absolutely wrecking the buzz for us amateur astronomers lately. I have had a brand new telescope for two weeks now with no clear nights to get my stargazing hat on.

“Oh, so you are the problem lately,” said David Moore of Astronomy Ireland, getting his digs in nice and early.

“We’ll be looking to the skies from 9pm, when it starts to radiate, and then all night long into dawn,” he added, changing the subject before I am given a chance to explain myself.

A good show, not a great show

Tonight’s meteor shower won’t be a record-breaker, as the Leonids peak roughly every three years, with 1966’s show a particular highlight when dozens of meteors a minute were recorded.

“We’re not expecting anything exceptional, but it should still be a good show,” said Moore. “We’d be happy with 40 meteors an hour in some cases.”

That’s Moore being conservative, with the Royal Astronomical Society in the UK claiming anything up to 100 per hour is doable “if we’re lucky”.

Actually on the back of, and in conjunction with, the Leonids, Astronomy Ireland is hosting a special moon watch on Thursday 19 November.

That’s because Uranus will come into view, which is a rarity in itself. “That should be a good one,” said Moore, “we think only one in a million people on the planet have ever seen Uranus live.”

Updated: This article was updated on 17 November, 5.20pm, to reflect that it is in fact Leo, not Perseus, from which the Leonids come. And at 18 November 9.45am. 

Leonids meteor shower appearing by the Milky Way image, via Shutterstock

Gordon Hunt was a journalist with Silicon Republic