Fifth Grade
Worksheets
Why Was the Earth So Hot?
The Earth was formed 4.5 billion years ago. It looked very different than it does today. There was no land. There were no oceans. There was no atmosphere. Life did not exist.
Scientists believe the Earth was very hot shortly after it formed. It was a mixture of molten minerals and elements. What caused the Earth to be so hot? There were likely three sources of heat.
The first source of heat was asteroids and meteorites. Asteroids are made of either metal or silica. They can range from one kilometer to almost one thousand kilometers in diameter. These asteroids collided with the Earth, giving off heat. Meteoroids are small pieces of rock. When these pieces fall to the Earth, they are called meteorites. Scientists believed that long ago there were many more meteoroids and asteroids in the solar system than there are today. Collisions with Earth were very common during its first 700 million years. These impacts created a huge amount of thermal energy.
