When the solar system formed, rocks (and other dense, heavy materials in the dust cloud such as iron and uranium) tended to gather closer to the Sun, and these materials combined together to form ...

The diagram shows the life cycles of stars that are: about the same size as the Sun; far greater than the ... falls together it gets hot. A star is formed when it is hot enough for the hydrogen ...

When you first learned about the Solar System, you probably saw diagrams that made it look orderly, with planets arranged in circular orbits around the Sun on a flat disk. But in reality, our Solar ...