The Earth.
The Earth formed approximately 4.6 billion years ago. It started as a ball of dust, ice and rock. As it grew, it's gravity mass increased. Because of this, more dust, ice and rock was pulled towards earth. Eventually, Earth grew to it's size in the present. Since it was so hot at the time, no life was supported on Earth.
The Earth formed approximately 4.6 billion years ago. It started as a ball of dust, ice and rock. As it grew, it's gravity mass increased. Because of this, more dust, ice and rock was pulled towards earth. Eventually, Earth grew to it's size in the present. Since it was so hot at the time, no life was supported on Earth.
The oceans on Earth weren't always there. To add to that, Earth wasn't this cold either. After Earth's creation, the temperature was well over 100ºC. After Earth cooled below 100ºC, all of the trapped water vapor in the atmosphere rose and made clouds. Then, it rained oceans. It took about 40,000 years to rain the amount of water that the oceans hold today. That's a lot of rain!
The oldest rock is about 3.8 billion years old. This rock was found in Greenland, and scientists used radioactive waves to see so deep in the ground.
Prokaryotic cells are simple cells. They are really the first form of life that came about on Earth. Prokaryotic cells also have no nucleus.
Eukaryotic cells are complex cells. Unlike the prokaryotic cells, these cells do have a nucleus.
Multi-cellular organisms are a type of organism that has more than one cell.
FInally, the Precambrian ended with a mass extinction. Every major geological time period ends with a mass extinction.