The fact we know this is happening, ahead of time, is exciting for scientistspublished at 07:11 BST

07:11 BST

Libby Jackson
Head of space at the Science Museum

This commission is exciting for scientists, because we know it's happening, and we know the speed and the mass of the rocket stage that will crash into the Moon.

We don't normally know that for meteors that crash into the Moon every day.

That means scientists will have a lot more information as they study the debris that will be caused by the collision.

By studying the light that is reflected from that material, scientists can determine its composition - helping them understand how the Moon has developed and how planetary systems evolved and were formed billions of years ago.

The collision between the Moon and a drifting SpaceX rocket is not thought to be dangerous, including to Earth, according to experts.

Nasa spokesperson Jimi Russel says while Nasa will continue to observe the site of impact for scientific purposes, "there is no danger to Earth".

Nasa scientists are planning to collect lunar data from the event and refine techniques for tracking objects in space.

"It's something really huge smashing into the Moon. It's not remotely dangerous, we can just watch the show," says Dr Matt Bothwell, public astronomer at the University of Cambridge.

Pallab Ghosh
Science correspondent

The story began in January last year, when a Falcon 9 rocket blasted off from Florida carrying two lunar landers into space.

The rocket's job was to fire its upper stage hard enough to send both landers out of Earth orbit and onto a path towards the Moon, and it succeeded.

But the spent stage was left drifting in a long, looping orbit that swung it out towards the Moon and back again.

Over the following 18 months, the gentle gravitational tug of the Earth, Moon and Sun - along with even the faint push of sunlight itself - gradually altered its path.

Astronomers tracking the object eventually worked out that those small nudges had put it on a course toward the Moon, picking up speed by the day and heading for an almighty crash.

Image source, AFP via Getty Images

A stray piece of a SpaceX rocket that has been hurtling in orbit at around 2.43 kilometres per second (about 5,400mph) is expected to collide with the Moon.

It's the upper section of a Falcon 9 spacecraft, about the size of a five-storey building and weighing at least 4,000kg.

The collision, according to US space agency Nasa, is predicted to happen at about 07:35 BST.

Experts say it will not be visible from Earth with the naked eye, but people with access to a sophisticated telescope may be able to see a flash radiating off the Moon's surface.

It is also not thought to be dangerous - including to Earth - with scientists instead considering this to be a unique opportunity to study what happens when an object hits the Moon.

Stick with us as we bring you the latest updates and expert analysis on what this all means.