Miles of air cover Earth. The boundary between Earth's atmosphere and outer space, the Kármán line, is about 62 miles (100 kilometers) above the planet's surface. However, about 99.9% of the mass of ...
Nov. 13, 2024 — An asteroid struck Mars 11 million years ago and sent pieces of the red planet hurtling through space. One of these chunks of Mars eventually crashed into the Earth and is one of ...