One pinhead of the sun's energy is enough to kill a person at a distance of 160 kilometers.
277
Mars had an oxygen-rich atmosphere around 4 billion years ago
13
It takes eight and a half minutes for light to get from the sun to earth.
159
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82
The Sun and Moon appear to be the same size because the moon is 400 times smaller than the Sun, but 400 times closer to Earth.
13
Saturn's rings are about 500,000 miles in circumference but only about a foot thick.
160
The Space Shuttle main engine weighs 1/7th as much as a train engine but delivers as much horsepower as 39 locomotives.
147
A comet's tail always points away from the sun.
2