The Geminids is one of the best meteor showers of the year for southern hemisphere observers. It is always worth staying up late (or getting up early!) to see them. And this year, 2017, the Moon will be absent, and the sky dark, for much of the night making for perfect conditions.
Meteor showers occur when Earth passes through the trails of dust left behind by comets. The dust follows the comet in its orbit around the Sun and creates meteors as it smashes into Earths atmosphere. The showers happen at specific times of the year and the next few days are the best for the Geminids – named for the part of the sky where the meteors appear to come from. In this case that is the constellation Gemini.
Australian observers should look to the north-east and north between about midnight and 3am on the nights of Wednesday December 13, Thursday December 14 and Friday December 15. You may also see a few Geminid meteors after these dates or before midnight. After about 3am on these nights the Moon rises and although it is a waning crescent meteors are always best viewed under a dark sky. If you are in a light polluted city or town it is best to move to a place with a dark north-eastern horizon.
What will you see? The parent body of the meteors is a “rock comet”, an asteroid (probably) which sheds grains of rock as it passes close to the Sun on each of its orbits. Since these grains are larger than the dust given off by a comet the Geminids appear as bright, long-lasting meteors. Every minute or two you will see a bright meteor trail across half the sky. Some flare up, some shatter into pieces and look like a sparkler!
Every Geminid meteor is different and waiting for the next one should keep you awake into the early hours.