Aliens almost certainly exist but humans should avoid making contact, Professor Stephen Hawking has warned.

In a series for the Discovery Channel the renowned astrophysicist said that to his mathematical brain, the numbers alone make thinking about aliens perfectly rational.

The real challenge is to work out what aliens might actually be like.

But he warned that aliens might simply raid Earth for resources, then move on.

If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans.

Professor Hawking thinks that, rather than actively trying to communicate with extra-terrestrials, humans should do everything possible to avoid contact.

He explained:

We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.

Read the full article at BBC News.