Today, Earth is covered with oceans and land, and it holds a lot of water.What caused this change? Scientists think that Earth's water came from asteroids and comets.
These asteroids and comets flew through space and crashed into Earth.
The ice on the asteroids and comets melted into water.
This is how water began to form on Earth.
Today, Earth is covered with oceans and land, and it holds a lot of water.
What caused this change? Scientists think that Earth's water came from asteroids and comets.
These asteroids and comets flew through space and crashed into Earth.
The ice on the asteroids and comets melted into water.
This...