Scientists have for the first time discovered a cave on the Moon.

At least 100m deep, it could be an ideal place for humans to build a permanent base, they say.

It is just one in probably hundreds of caves hidden in an “underground, undiscovered world”, according to the researchers.

Countries are racing to establish a permanent human presence on the Moon, but they will need to protect astronauts from radiation, extreme temperatures, and space weather.

Helen Sharman, the first British astronaut to travel to space, told BBC News that the newly-discovered cave looked like a good place for a base, and suggested humans could potentially be living in lunar pits in 20-30 years.