What are comets made of?
What are these blazingly bright balls in the sky and where do they come from?
Words by Scott Dutfield
Taken in 2013, this image of Comet Lovejoy was snapped when it was almost 60 million kilometres from Earth
© NASA/MSFC/Jacobs Technology/ESSSA/Aaron Kingery
They’re known as cosmic snowballs, but rather than compacted snowflakes, comets are frozen balls of gases, rock, ice and dust in huge orbits around the Sun. You wouldn’t be able to hold one in your hands either, as they can be the size of a small town. When they approach the Sun and heat up, they release massive tails of gas and dust that can stretch for millions of kilometres behind them.