The solar system: Why do comets have tails?

Did You Know: Space – Why do comets have tails?

Comets are made of gas, dust, and ice that was left over from when the solar system formed. Comets do not have tails all the time. When a comet passes close to the sun, it heats up, causing its surface to boil away and create a tail.

How comet tails form

Comets travel around the sun in an oval-shaped path. As a comet passes close to the sun, it starts throwing out dust and gas because the nucleus is heated by the sun. This form a tail that points away from the sun

Comet’s nucleus

The head of a comet is called the nucleus.

It is often known as a “dirty snowball.


This cloud of dust and ice around the comet’s nucleus is called the coma. This is where the tail starts to form as the “snowball” melts.

Comet’s tail

The comet’s dust tail streaks across the sky for many millions of miles. The tail always points away from the sun.

Is it possible to land on a comet?


After a 10-year journey across our solar system, the Rosetta spacecraft successfully sent a lander, called Philae, onto the surface of a comet in 2014.