A meteor from the 2009 Geminid meteor shower darts through the constellation of Hydra, close to the star Alphard, as captured by Pete Lawrence. Credit: Pete Lawrence
The annual Geminid meteor shower will put on a celestial show over the next few nights, with some predictions suggesting that almost 100 meteors per hour could be spotted shooting across the night sky. Meteors are produced when tiny pieces of space dust enter our atmosphere at enormous speeds. As they do the air ahead of them is compressed violently causing it to heat up. This tremendous heat in turn makes the meteor glow as it streaks across the sky. It’s amazing to think that the average meteor is created by a piece of celestial detritus no bigger than a grain of sand.
Ordinarily on a clear dark night you might see a handful of meteors every hour. These are known as ‘sporadic’ meteors as they don’t belong to a particular shower. However when a meteor shower is underway there’s a good chance you’ll see many more, as the shower is supplementing the handful of sporadic ‘shooting stars’.
Meteor showers occur when the Earth passes through a trail of debris left by a comet as it passes through the Solar System. The particular object that creates the Geminid meteors measures around 5km in diameter and is known as 3200 Phaethon. It was found in the early 1980s and is in fact designated as an asteroid, though it certainly has some cometary traits. Perhaps, some have argued, it is a ‘dormant’ comet.
If you go out over the next few nights and see any meteors you’ll know you’ve spotted a Geminid if it appears to come from a point in the constellation of Gemini. This point is known as the ‘radiant’ and it’s the constellation that the radiant is in that gives the shower its name; so the Geminids come from Gemini, the Orionids come from Orion etc.
In terms of where to look, my advice would simply be to look up. Gemini is very high in the sky over the next few nights at around 1:30am and with a Moon that isn’t going to cause too much trouble we’ve got some good observing conditions for this year’s shower. Wrap up warm and sit back in a sun-lounger if you can as this should stop your neck from getting tired and give you a better, more comfortable, view of the sky. Meteor showers like the Geminids are a great chance to get together with friends to observe too, as the more eyes the better. You can join in with the special Geminid ‘Meteorwatch’ event on Twitter by tagging any Geminid meteor observations you tweet with the hashtag #meteorwatch.
The actual peak of the Geminid meteor shower will occur at around 5am (UK time) on Monday morning when the constellation of Gemini will be sitting in the west, around 40 degrees above the horizon, as seen from the UK. Even so there have already been several reports of Geminid meteor sightings. So if it’s clear where you are, go outside over the next few nights and see what you can see!