Earth & Space
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Planets, weather, oceans and the sky above them.
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Why a cannonball fired hard enough never lands: Newton's cannon and the orbit
Fire a cannonball horizontally from a mountaintop and it lands some distance away. Fire it harder and it lands farther. Fire it hard enough and the Earth's…
Why astronauts float: the space station never stops falling
Astronauts on the International Space Station look weightless, but at 400 km up, Earth's gravity is still about 90% as strong as on the ground. The trick is…