Break out the chaise lounges, blankets, and hot chocolate tonight: The Leonid meteor shower is back.
Thank a comet, named 55P/Tempel-Tuttle, for the annual November show. The comet, which orbits the sun once every 33 years, crosses Earth's orbit, ensuring that the debris Earth encounters is relatively dense compared with debris in other comet-generated meteor showers.
That can mean a spectacular show during years when the comet makes its closest approach – and when it's heated enough to shed copious amounts of debris. Alas, that's not this year.
During typical Leonid showers, skywatchers see an average of 15 meteors an hour, according to Donald Yeomans, who studies comets and asteroids at NASA's Jet Propulsion Laboratory in California. But once the comet reaches Earth's orbit on its way to and from the sun, meteor showers can become meteor storms, with thousands of meteors flitting across the sky each hour.
Tempel-Tuttle last passed this way in 1998. So this year, astronomers estimate a modest 20 meteors an hour at peak viewing.
The best viewing opportunity overnight will take place during the final two to three hours before dawn on Nov. 18. Assuming good weather, the number of meteors you can see depends on how free the night sky is of the glow from city lights, how much of the sky you can see free of trees and hills, as well as how dense the debris is as Earth plows through it.
The meteors are called the Leonids because they appear to originate from within the constellation Leo. So in getting set up to watch the shower, try to find a spot where you can see as much sky as possible, including the constellation, while in that comfy chair or chaise lounge.
Some experts suggest picking out a patch of sky and watching it for 15 to 20 minutes; you're more likely to spot something that way than if you are randomly scan the entire sky.
And avoid looking into lights to preserve your "night" vision. Often meteors are faint. The better adapted your eyes are to the dark, the more meteors you'll see.
This is definitely a naked-eye event. Binoculars and telescopes have a field of view that's far too narrow for watching meteors. Save those for comet-watching.