The Geminids can be found in the constellation of Gemini in the night sky, hence their name. They are not aliens however they are a meteor shower. The asteroid 3200 Phaethon is orbiting the sun in our solar system and is dragging after it a tail of dust particles. Each year in mid December the earth barrels through the tail creating a spectacular night time display. This year it is on 13th December. The particles causing the meteor shower are travelling at approximately 80,000 mph when they hit our atmosphere and burn up.

You, the readership of The Green Man, who are naturally more intelligent than average, will have no doubt raised your collective eyebrows at an asteroid having a tail. Of course we all know that comets typically have tails and asteroids don't. Since you already know this I don't need to explain that comets are made up of ice, dust and gravel, which facilitates the tail, where as asteroids are solid lumps of rock. Scientist speculate that 3200 Phaethon has collided with another asteroid or comet and picked up some debris as a tail in the process.

Here is a cellestial map courtesy of NASA to help you find the Geminids. The best time to look is around midnight of 13/12/04.

Read more at the NASA website.