Cosmic Space

Geminids could be a gem of a meteor shower

The stars have aligned for this weekend’s peak of the annual Geminid meteor shower. Now let’s hope that the weather aligns as well.

Skywatchers rank December’s Geminids alongside August’s Perseids as the year’s highlights for meteor shows. Under peak conditions, sharp-eyed observers can see two meteors a minute. NASA notes that the shooting stars are bright and fast, and tend to be yellow in color.

But the strength of the show is highly dependent on viewing conditions. In some years, the moon’s glare washes out the night sky so that few meteor streaks stand out.

One of the few good things about 2020 is that the moon won’t interfere this year. It’s nearly a new moon, which means skywatchers will see only a thin crescent that rises in the east just before dawn.

The Geminids get their name from the fact that the meteor flashes appear to emanate from a central point, or radiant, in the constellation Gemini. Those flashes are created by bits of grit from a comet-like asteroid called Phaeton, whose orbital track intersects with Earth’s.

Every December, when our planet passes through the diffuse trail of debris left behind by Phaeton, some of that debris zips through the upper levels of the atmosphere, leaving ionized trails in their wake. That’s what we see as shooting stars.

Geminid meteors start popping up around Dec. 4, but they reach their peak on the night of Dec. 13-14 and fade away by around Dec. 17.

To maximize the viewing experience, you should get as far away as possible from the glare of city lights. Although the meteor shower’s radiant is in Gemini, shooting stars can appear in any region of the sky — so it’s good to find a spot where your view is free of obstructions.

You may want to bring along a lounge chair or a blanket to lie on, a warm jacket or a sleeping bag to ward off the December chill, and a thermos of hot beverage. Be sure to give your eyes a chance to adjust to the dark. If the skies are clear and glare-free, meteors could make their first appearance as early as 8 to 9 p.m. They typically reach their peak around 2 a.m. and then fade into the glow of the rising sun.

The biggest variable may well be the weather. What good is it to have dark, wide-open skies if they’re hidden behind the clouds? Check out the Clear Sky Chart or the National Weather Service’s digital forecast for your locale. (Select “Sky Cover %” from the menu.)

Meteors aren’t the only attraction in the night sky. While you’re looking up, check out Jupiter and Saturn in western skies after sunset. They’re heading toward an unusually close conjunction on Dec. 21, which is the longest night of the year in the Northern Hemisphere.

Mars, which recently went through this year’s closest approach to Earth, is glowing butterscotch-bright farther east. If you’re up during the wee hours of the morning, you may see Venus and the crescent moon rising over the eastern horizon. And if you’re in just the right place at the right time, you might even be able to spot the International Space Station or some of SpaceX’s Starlink satellites.

By Alan Boyle

Mastermind of Cosmic Log, contributor to GeekWire and Universe Today, author of "The Case for Pluto: How a Little Planet Made a Big Difference," past president of the Council for the Advancement of Science Writing.

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