The Geminids are due to peak tonight, sowrap up warm and head out under the stars, and you'll be in with a chance of seeing the brilliant Geminid meteor shower.
The celestial spectacle is set to shoot streaks of light across the night sky from now until 17 December, peaking tonight, in the early hours of 14 December (clouds permitting, after the moon has set in the small hours).
The Geminids may not be the most active shower of the year, but amateur astronomers in the UK can still expect to see up to an estimated 60 meteors each hour during its peak.
So, where will the Geminid meteor shower be visible? What causes it in the first place? And when exactly should you look for it? All of this (and more) is answered below by Professor Simon Green, one of the astronomers who discovered the source of the Geminid meteors in 1983.
If you’re looking for more stargazing tips, be sure to check out our astronomy for beginners guide and ourfull Moon UK calendar.
Where will the Geminid meteor shower be visible?
In the Northern Hemisphere, look towards the constellation Gemini. You can find Gemini by first looking for Orion the Hunter (check out our beginner’s guide to astronomy if you need a refresher), which under clear skies, should be easily distinguishable by the three bright stars (Mintaka, Alnilam and Alnitak) that make up Orion’s Belt.
From Orion, look up and to the left – and you’ll see the two bright stars, Castor and Pollux from the constellation Gemini, high in the sky. This is where the Geminids appear to originate, but for a chance to see meteors with longer tails (the result of travelling further distances away from the source), it’s best to look slightly away from the constellation: “You actually want to look to one side [of the constellation Gemini], so you see them flying past. They tend to go across the whole sky, appearing to have come from Gemini,” says Green.
The Geminids can be graceful, fairly slow-moving, and on a good night, you may be able to see as many as two per minute. The Geminids often appear in clusters, so if you see one – keep your eyes peeled for more!
The Geminid meteor shower will peak tonight, the night of 13/14 December 2021.
When can you see the Geminid meteor shower 2021 in the UK?
The Geminids are expected between 4 – 17 December 2021, and they'll peak early in the morning of 14 December.
"The most important thing is that if you want to observe the Geminids, you have to go out preferably after midnight," says Green. "The constellation of Gemini, which is where the Geminids appear to come from, will be high in the sky around 1–2am."
Green says that the Geminid meteor shower is quite reliable, and stargazers see roughly the same numbers of meteors every year.
"However, this year there is a very bright blue Moon which doesn't set until about 3am," says Green. "A bright Moon makes the sky bright, which makes it hard to see the meteors.
"This year, the best time to go I would say is to go out about 3:30 in the morning and look up. Gemini is still quite high at that point, but the sky will be much darker."
What should you do to get the best chance of seeing them?
To get the best view of the Geminid meteor shower, you'll need to head out a bit earlier so that you can find a dark spot and let your eyes get used to the darkness for 20-30 minutes.
"Wrap up very warm. Take a chair out, maybe a hot water bottle and a sleeping bag," suggests Green. "Then just look up. You don't need binoculars, you don't need anything: just your eyes. Then you should see a meteor every minute or two."
The meteors will appear to come from the Gemini constellation, which you can find using a star chart or an astronomy app.
"If you don't know the sky, it won't matter, as you don't really need to find Gemini," says Green. "Because the direction that the meteors appear to be coming from is not necessarily the direction you want to look at. You actually want to look to one side so you see them flying past.
"They tend to go across the whole sky, and if you're out stargazing with the family you can look in opposite directions of the sky and just shout each time you see one. By the time somebody turns around, it will have gone, but between you you can have a competition who sees the most."
Where do the Geminid meteors come from?
Though they appear to originate from the Gemini constellation, the meteors actually come from an asteroid called 3200 Phaethon – an asteroid that was discovered by Green and a team of astronomers nearly 40 years ago.
Green was part of a team in 1983 that was set up to discover new, fast moving asteroids.
"In fact we discovered six comets from May to November that year, but I was getting a bit despairing that we would find any asteroids, which is what we were looking for," recalls Green.
"Then we got to November, and this incredibly bright source appeared. It was seen multiple times moving and I was absolutely certain it was real."
Verified a few weeks later, Green and the team went on to calculate the asteroid's orbit. They realised that 3200 Phaethon's orbit was rather unusualfor an asteroid, in that its orbit is more similar to what we know of comets – rather than asteroids. Many astronomers also agree that its composition points to a possible cometary origin, and Phaethon has been classified as an F-Type asteroid.
"It went closer to the Sun than any of the known asteroids," said Green.
"Then after the orbit was defined, famous cometary scientist Fred Whipple noticed that the orbit looked the same as the orbits of the Geminid meteor stream."
Read more:
- How often do large meteorites hit the Moon?
- The best 5 apps all stargazers should download right now
People on Earth are able to see the meteor shower when our planet passes through the orbit of the asteroid.
"For certain meteor showers that happens once a year. But there are lots more meteor streams out there, only we can't see them because the Earth doesn't pass through them."
How many meteors will be in the sky?
"The rate is defined by something called the zenithal hourly rate, which is the number of meteors you would see if the stream was overhead. For the Geminids in 2021 that number is 120, which means if you could see every single meteor, you would see one every 30 seconds.
"But of course, viewing from the UK will be different," says Green. "Typically, in Britain, you get about half that rate one every minute or so."
About our expert, Professor Simon Green
Professor Green is a senior lecturer in planetary and space sciences at The Open University. In 1983, he was one of the astronomers who discovered the asteroid that is responsible for the Geminid meteor shower.
