Up for a meteor shower? Good, because there’s one starting now, called the Geminid Meteor Shower. It actually takes place starting around the 7th of December and peaks around the 13th or 14th. It’s called the “Geminid” shower because the meteors it delivers to Earth’s atmosphere seem to radiate from the constellation Gemini. Think of it like driving through a dust cloud or a snowstorm and seeing particles coming at you from the same point just ahead.

In a good year, observers may see up to 120 Geminid meteors per hour. However, this year, it may not be so great because of moonlight. The Moon is just past full (it’s waning gibbous). That means the skies will be brightened by moonlight, which will wash out the dimmer meteors. But, it’s still worth checking out because the shower usually does deliver some bright meteors. If you do go out, dress warmly, and try to find a location where you can stand to block out the Moon. They’re definitely worth checking out and if you want more info on what you might see, check out about viewing conditions.

What Causes the Geminids?

Meteor showers originate in swarms of ice, bits of dust, and pieces
of rock the size of small pebbles that exist in the solar system in streams. Where does all that solar system flotsam come from? Most of it streams away from comets as they orbit the Sun. As they get closer to our star, their icy cores get warmed up. That causes the cometary nucleus to lose material. Eventually, all that debris spreads out along the path of the comet. Some streams also come from asteroids.

Most of the time, all that debris stays in space. But, in certain times of the year, Earth intersects those streams as it pursues its own orbit around the Sun. There are about 21 or so that it does encounter. They are the sources of the best-known meteor showers we can observe. They occur when the cometary and asteroid debris slams into our atmosphere. The friction between the pieces of rock and dust and the gases in our atmosphere heats up the debris. Most of the time that’s enough to vaporize these bits of ice and rock well before they reach the ground. When that happens, we see a meteor. If a piece of the meteoroid happens to survive the trip and falls to the ground, we call that a meteorite.

In fact, the Geminids themselves are the product of the asteroid 3200 Phaethon. Although it’s a rocky body, it also ejects material as it makes its way around the Sun each year. Earth intersects its swarm of debris during the first three weeks of December every year. That intersection point happens to be lined up against the Gemini constellation. That’s why its meteors appear to come from that direction.

Watching the Geminid Shower

For folks in the colder parts of the Northern Hemisphere, catching the Geminids is an exercise in staying warm. One year, I viewed the Leonids (in November) from our front yard in Massachusetts. It was pretty cold. So, I had the idea of running my car for a few moments and then lying on the warmed hood. That’s not terribly fuel-efficient, so I don’t recommend it. In more recent years, I just dressed very warmly. Sometimes, I have a lawn chair to relax in and simply gaze at the sky waiting for meteors.

The best viewing hours are usually after midnight. That’s when Gemini is higher in the sky. However, those can also be the coldest times. So, bundle up and take a warm beverage out with you! While you’re viewing, check out the colors of the meteors you see. Each color (blue, red, white, etc.) indicates a different chemical element that is being heated as the meteor heads through our atmosphere. I’ve written about this shower before, and am always interested to see how good it will be each year.