Do you know what a volcano is?

A volcano is a mountain. But a volcano is not an ordinary mountain.

A volcano can erupt!

When a volcano erupts, hot gases come out.

When a volcano erupts, hot ash comes out.

When a volcano erupts, hot, melted rocks come out. A volcano eruption can be very bright and dangerous!

What makes a volcano erupt? First, let's talk about what makes a volcano!

Inside the Earth, there is hot, melted rock.

This hot, melted rock is called magma. Sometimes, the magma rises up.

It comes out of the Earth. It comes through the opening of a volcano! The opening of a volcano is called the crater.

When a volcano erupts, magma comes out through the crater! When magma comes out of a crater, it is called lava.

What happens when lava comes out of the volcano? Sometimes, lava comes out slowly. Sometimes, lava comes out very quickly! The lava runs down the side of the volcano.

It cools down. It hardens.

It becomes part of the mountain!

Can all volcanoes erupt? No! Not all volcanoes can erupt. Some volcanoes can erupt. These are called active volcanoes.

Some active volcanoes erupt very rarely. Some active volcanoes erupt every day! Did you know: There are more than 1,500 active volcanoes on Earth! Some volcanoes have not erupted for a long time. These are called dormant volcanoes

Dormant volcanoes might have erupted hundreds of years ago. Dormant volcanoes are like sleeping volcanoes. They might wake up one day and erupt again!

Some volcanoes will never erupt again. These are called extinct volcanoes.

Extinct volcanoes are very old! There are volcanoes all around Earth. Did you know: About twenty volcanoes erupt on Earth every day! There are volcanoes under the sea!

Some are small. You cannot see them above the water. Some are big. They become islands!

Did you know: There are about 1,000 volcanoes under the sea! There are even volcanoes in space! Many planets in space have volcanoes. Olympus Mons is a volcano on Mars.

It is the biggest volcano in the solar system! Volcanoes are everywhere. Volcanoes are awesome! But don't get too close!