December isn’t just about the holidays — it’s also the time of year we get to enjoy what is often touted as one of the best meteor showers of the year: the Geminids.
The Geminid meteor shower has been underway since Dec. 2, but it peaks this week, on the night of Dec. 13-14.
But even if you have clear skies, there’s a little problem: the moon.
“Usually I’m excited to tell everybody the Geminids is the one shower you can get out right after supper and enjoy,” said Peter Brown, Canada Research Chair in Meteor Astronomy and a professor at Western University in London, Ont. “And you could still do that this year, but with the moon, it’s really going to crimp things.”
With most meteor showers, the radiant — or the constellation from which the meteors appear to originate — tend to rise later into the night, such as the summer Perseid meteor shower, which is also considered to be one of the best showers of the year.
With the Geminid meteor shower, Gemini rises around 7 p.m. local time, allowing those who may not want to stay up until the wee hours of the morning to catch a glimpse of some meteors.
However, this year, the moon will be almost 97 per cent illuminated and fairly high in the sky early in the evening, which means you’ll only be able to see the brightest of the Geminids.
Here’s where the good news comes in: the Geminids tend to produce bright fireballs, so you’ll still have a good chance of seeing some meteors.
From the sky to the ground
Meteor showers occur as Earth plows through leftover debris from comets or — rarely — asteroids. In this case, the Geminids come from the asteroid 3200 Phaethon.
As the small particles burn up in our atmosphere, they appear as streaks in the sky, or as some like to call them: “shooting stars.”
But the Geminids are special.
Brown says that one of the interesting things about the Geminid meteor shower is that they often drop meteorites, pieces of its parent object that reach the ground.
“I mean, you could actually go out and find a Geminid, a piece of Phaethon,” he said.
To date, however, no one has been able to find them, he said, but they’re out there.
Another thing that is special about the Geminids, Brown said, is a lot of them reach the moon.
“Of all the meteor showers, you can see the Geminids hitting the moon the most,” he said. “If the geometry is right, and you’ve got the right lunar phase, and the Gemini peak is just in the right geometry, you can see as many as one lunar impact flash from the Geminids every 20 minutes.”
Many more meteorites reach the lunar surface than land on Earth because the moon doesn’t have a thick atmosphere where the debris would burn up.
In fact, it’s believed that astronaut Harrison “Jack” Schmitt, the only geologist to ever walk on the moon, saw a lunar impact flash while he was in orbit on Dec. 12, 1972, which may have very well been a Geminid.
How and when
The August Perseids and December Geminids volley back and forth for the title of the best meteor shower of the year, mainly because the Perseids occur in fairer summer weather and have a greater chance for clear skies. Whereas the Perseids can produce 100 meteors an hour under ideal conditions, the Geminids can produce upwards of 150 per hour.
December tends to be not only cold, where people don’t often spend nights outside, but it’s also cloudier. Be sure to check on the weather in your area for the night of the peak.
If you see you may be clouded out on the night of Dec.13-14, the Geminids tend to be fairly active in the day or two leading up to and after the peak. So plan ahead.
Make sure you bundle up, get to a dark sky site away from city lights and just look up. You don’t need to look toward Gemini, which is the radiant in this case. And make sure not to look away: meteors are fast and you might miss a great fireball.
And if you’d like to keep an eye on meteor shower activity, check out this site from Western University’s Meteor Physics Group and the Global Meteor Network, which tells visitors how many meteors there are in an hour.