New research suggests that our trusty companion may not have been the Earth's first, but formed from several smaller moonlets.

Politician Douglas Carswell has been arguing with scientists about what causes the tides. We've figured out who's right.

Why today is 24 hours and 1 second long.

The Universe's expansion may not be accelerating as fast as we thought.

The telescope discovers the oldest solar system to date.

A little trig helps to find the relative distance to the Sun and Moon.

If you like to have your mind blown cosmology is a great field to go into. But is it science?

Images are now being taken on the world's most powerful digital camera. For over 500 nights over the next five years the Dark Energy Camera will photograph the light from more than 100,000 galaxies up to 8 billion light-years away in each image.

Some of the things I overheard at Stephen Hawking's 70th birthday conference did make me wonder whether I hadn't got the wrong building and stumbled in on a sci-fi convention. "The state of the multiverse". "The Universe is simple but strange". "The future for intelligent life is potentially infinite". And — excuse me — "the Big Bang was just the decay of our parent vacuum"?!

This is the first part of the lecture given by Astronomer Royal Martin Rees at Stephen Hawking's birthday symposium.