The secrets of the universe are set to be explained to kids by one of the world's cleverest people.

Professor Stephen Hawking has announced he's going to write a book with his daughter Lucy to explain things like black holes and the start of time.

He's already written a best seller, called A Brief History of Time, on the same subject for adults.

He described his planned book as "a bit like Harry Potter in the universe, about science, no magic".

He'll be getting help thinking like a kid from his daughter's eight-year-old son.

At the same time, Professor Hawking said he thinks people will have to set up homes on other planets and around other stars if we are to stay alive.

He predicted there would be a settlement on the Moon in 20 years, and another on Mars within 40.