Mars had an oxygen-rich atmosphere around 4 billion years ago
13
Venus is the only planet that rotates clockwise.
310
Summer on Uranus lasts for 21 years.
358
The density of Saturn is so low that if you were to put it in a giant glass of water it would float.
219
Jupiter has radio storms so strong that they can be picked up and heard by an AM radio.
16
Sound doesn't travel in space.
255