A comet

📖 In short

A comet is an icy body that goes around the Sun on a very long oval path. When it gets close to the Sun it heats up and gives off gas and dust, so a long shining tail appears in the sky, like a flying star's hair!

🤩 Did you know?

Comets formed along with the planets about 4.6 billion years ago.
Comet Shoemaker-Levy 9 crashed into Jupiter in 1994.
Some comets' tails stretch more than 100 million kilometers.
Most comet nuclei are 16 kilometers across or less.

🔎 Find out more

🌟 A dirty snowball

A comet's core is called the nucleus, like a dirty snowball made of ice, dust and rock, only a few kilometers across.

🔍 Head and tail

As a comet nears the Sun, a big cloud of gas and dust forms around the nucleus, called the coma or head. Sunlight pushes it out into a tail, which always points away from the Sun.

💡 Halley's Comet

The most famous comet is Halley's Comet, which can be seen from Earth about every 76 years. A person may see it once or twice in their life. It will be back in 2061.