What is 'Planet Nine'?

There are 10 times more galaxies in the universe than previously thought

The supermoon: 4 things to know

Hubble spots dying star shooting massive plasma 'cannonballs'

NASA is growing a Martian garden to prepare for life on Mars

Nearest Earth-like exoplanet might be an ocean world

Look to the skies for 6 weeks of meteors

How to see the Draconid meteors at their peak

Richard Branson wants to bring 'sexy hotels' to space

World's largest telescope now ready to receive messages from E.T.

Elon Musk thinks we should all move to Mars

6 things we learned from the Rosetta spacecraft