Meteor Shower Viewing Guide: The 2020 Geminids

Facts Worth Sharing

  • The 2020 Geminid meteor shower peaks on the night of 13 and 14 December, with the best viewing after midnight on the morning of 14th. You may also see meteors a day or two before and after the 14th.
  • To watch, go to the darkest place you can, let your eyes adjust for several minutes, and then look directly overhead.
  • The annual Geminid meteor shower is caused by debris from asteroid Phaethon.

The 2020 Geminid meteor shower peaks on the night between 13 and 14 December. The Geminids are usually the best meteor shower of the year, producing 100 or more meteors per hour at a dark site. This year's show may be particularly good thanks to a new Moon on 14 December that will keep the sky dark all night long.

The Geminids are caused by debris from an asteroid called 3200 Phaethon. Phaethon's 524-day orbit carries it closer to the Sun than any other asteroid: roughly 21 million kilometers, less than half the distance of Mercury's closest approach to the Sun.

Asteroid 3200 Phaethon
Asteroid 3200 Phaethon Asteroid Phaethon, seen here in radar images from the Arecibo Observatory radar telescope, is the litterbug responsible for the annual Geminid meteor shower.Image: Arecibo Observatory/NASA/NSF

What is a meteor? 

Meteors are streaks of light in the sky caused by space stuff (a technical term) burning up as it hits the Earth's upper atmosphere at very high speeds (tens of kilometers per second). That space stuff usually consists of small dust and sand-sized dirt and rocks. Even these small particles can cause streaks of light you can see from the ground at night. As an approximation, the bigger the dirt that hits, the brighter the light. Space is full of this dust; on a typical night from a dark location, you might see up to 10 meteors per hour—no meteor shower required!

What is a meteor shower?

Meteor showers occur when the Earth passes through debris shed by a comet that flew through the inner solar system sometime in the past. They reoccur at about the same time every year, when Earth comes around in its orbit and passes through the comet dust again.

Two of the best meteor showers of the year are the Perseids, which peak around 12 or 13 August, and the Geminids, which peak near 13 and 14 December. The Perseids often get more media attention because they occur during the northern hemisphere summer. However, the Geminids typically produce more meteors. While the Orionids are typically not one of the largest showers, this year the first quarter moon sets a couple of hours before midnight, leaving the sky dark. You could see as many as 20 meteors per hour from a dark sky site.

Meteor showers are named after the constellation that contains the radiant of the shower. The radiant is where the meteors appear to emanate from—if you draw a line back along the meteors, all of the lines will meet at the same point. This is an effect of the Earth speeding through the comet debris, meaning when you see a meteor, you're seeing direct evidence of our planet orbiting the Sun!

How to watch a meteor shower

All you need to watch a meteor shower is your eyes, patience, and a (mostly) cloud-free night. Go out, get comfortable, and stare at the sky. Typically the best time to see a meteor shower is between midnight and pre-dawn, because that's when you are on the leading side of the Earth, watching the comet debris come at you like rain hitting a car windshield.

You don’t have to stare in the direction of the radiant; in fact, meteors farther away from it will appear longer. It is often said that an ideal place to look is 45 degrees away from the radiant, but the most important factor is getting to a dark location away from city lights, letting your eyes adjust for several minutes, and looking at the darkest patch of sky you can. 

Go out, look up at the night sky and have fun!