Mars had an oxygen-rich atmosphere around 4 billion years ago
13
A neutron star (what remains after a Super Nova) is so dense that a portion of it the size of a sugar cube would weigh as much as all of humanity, or more than all the cars in the United States.
5
Astronauts cannot burp in space.
232
Saturn's rings are about 500,000 miles in circumference but only about a foot thick.
160
A comet's tail always points away from the sun.
2
Some asteroids have other asteroids orbiting them.
131
There are 5 to 10 times more stars in the known Universe than there are grains of sand on all the world's beaches, but a single grain of sand has more atoms than there are stars in the known Universe.
20