The diameter of the Milky Way is a billion billion kilometres.
Our brain cells do look a lot like a map of the universe – but that doesn't mean they're the same thing.
"Sometimes I've believed as many as six impossible things before breakfast." To understand the universe, we need more Mad Hatter mathematicians.
New observations show we don't really understand the universe's expansion.
It's like one great big distillery up there.
What caused the Big Bang is still a mystery. And that's just one of the many unanswered questions, in spite of everything we do know about the birth of the Universe.
The Astronomer Royal answers some of the world's – and the universe's – biggest questions.