Transcript: Earth’s atmosphere is unique within the solar system mostly because of the nitrogen and oxygen that form the bulk of the Earth’s atmosphere: 75 percent nitrogen, 20 percent oxygen, plus carbon dioxide, argon, water vapor and other trace gasses. The weather on the Earth is generated...

Transcript: The ancient Greeks knew about loadstones. These were curtain rocks which, when suspended in a fluid, would appear to line themselves in response to a mysterious force. That mysterious force was magnetism, first understood through the experimentation of the physicist Michael Faraday....

Transcript: Cratering affects the evolution of planets. The cratering history of the Earth has varied over its history. Cratering was much stronger in the first half billion years when there was plenty of debris left over from the formation of the solar system. When you look at the Moon we are...