Geminid Meteor Shower: Shooting Stars Tuesday, Wednesday
Shooting stars as Earth passes through debris from an asteroid
Dec. 13, 2011 — -- Stay up late, or get up early, and if the weather is clear you may get to enjoy the Geminids, the last sizeable meteor shower of 2011.
The best viewing, say astronomers, is Tuesday or Wednesday night, starting after 10 p.m., local time, and lasting until dawn. We're just a few days past a full moon, so the waning gibbous moon will be high in the sky after midnight, when meteors are usually at their peak. Even so, if the seeing is good where you are, you could well see about one shooting star per minute, and perhaps spurts of more.
The worst thing for skywatchers in the northern hemisphere this time of year is that the air is often cold and crisp -- but the best thing this time of year is that the air is often cold and crisp. You have to bundle up, but if the sky is clear, it's very clear.
Be alert; most meteors streak by in a second or less, sometimes in clusters. The best way to see them is to find a nice, dark place with no street lights and as few trees as possible, and look up. You may be happiest in a lawn chair or a sleeping bag. The streaks could appear anywhere in the sky.
It may help if you park yourself so that the moon is blocked by trees or a building, but then part of the sky will be blocked too. It's important for you to let your eyes get used to the darkness.
The Geminids, which happen this time of year like clockwork, are an oddity. Most major meteor showers -- the Perseids in August, the Leonids in November -- have occurred for thousands of years, caused as Earth passes through clouds of debris left by passing comets.
But the Geminids only appeared in the 1860s. Not until 1983 did astronomers figure out their origin. They found an asteroid, 3200 Phaethon, in a lopsided orbit that crosses our own and also brings it close to the sun -- close enough that the sun's heat probably cracks it and kicks up dust, which, over time, has spread out along the asteroid's path. We're passing through the dust clouds; the shooting stars are pieces, no larger than grains of sand, burning up as they plow into the atmosphere.
In general, there are more shooting stars in the morning hours because that's the side of the Earth that faces forward as we orbit the Sun, so it's less shielded. While the shower actually peaks tonight, meteors are often spotted several nights before and after.
You don't need any special equipment, though a lawn chair and a sleeping bag might be good to bring along. Get away from cities if you have the option. (Go to our weather page for conditions near you.) Astronomers will tell you that meteor showers are best if you regard them as something to be savored, rather than awed by.
But Alan MacRobert, senior editor at Sky & Telescope magazine, said meteor showers can be great fun.
"The colder it is, the more it's an adventure," he said in an email. "Just wait till the Quadrantid shower, predicted to be excellent on the morning of this coming January 4th. ... Experienced meteor watchers will be dressing for this like for an Arctic expedition."
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