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
If two pieces of metal touch in space, they become permanently stuck together.
808
It takes a photon 170,000 years to travel from the core of the Sun to the surface, but only 8 minutes to travel the rest of the way to Earth.
6
Summer on Uranus lasts for 21 years.
358
If NASA sent birds into space they would soon die; they need gravity to swallow.
146
There are more nerve cells in the human brain than there are stars in the Milky Way.
349
Mars had an oxygen-rich atmosphere around 4 billion years ago
13