Britons will be able to see a rocket hurtle across the sky at 10.15pm tonight – as it loops around the Earth two hours after taking off from America.
The Falcon 9, the first manned space flight to leave US soil for nine years, is set for blast off from Cape Canaveral, Florida, at 8.22pm BST (15.22 EDT).
It will then loop up to the International Space Station and pass low along the south-west of the UK skyline.
The historic space flight by Elon Musk’s SpaceX will mark the first time a private company has put astronauts into space.
It is the second attempt to launch after Wednesday’s flight was aborted because storm Bertha had rolled in off the Gulf of Mexico, obstructing the flight path.
This map shows the rough path the spacecraft is expected to take across the UK sky tonight, providing the launch goes ahead. Pictured left is the Crew Dragon spacecraft
The route the spacecraft is expected to take over Europe is pictured above. It will be visible in the south-western part of the British night sky
NASA and SpaceX are gearing up to send two American astronauts to the International Space Station aboard an American rocket
NASA astronauts Robert Behnken and Douglas Hurley were strapped in the cabin of Crew Dragon Capsule ready for blast off when the launch was cancelled on Wednesday
The rocket is expected to swoop low over the south-western horizon and zoom past the left side of the moon before disappearing.
It will appear as a tiny shining dot as it shoots across the night sky after sunset at 9.05pm.
The Met office has forecast clear skies for most of the UK on Saturday night, making the rocket easier to spot.
A spokesman told MailOnline: ‘After a warm and sunny day on Saturday, much of the UK can expect clear skies on Saturday evening, with perhaps a little low cloud developing along the Scottish Borders and Northumberland coastline later in the night.’
Britons can also watch the launch as it happens on NASA’s TV channel, which is streamed on YouTube.
The mission was cancelled as storm Bertha rolled into the area. Pictured above is the rocket on Wednesday moments before the launch was cancelled
Wednesday’s launch was cancelled as bad weather meant the launch had to be delayed by a few seconds – meaning it would miss its trajectory for arrival at the fast-moving ISS.
NASA astronauts Bob Behnken and Doug Hurley were strapped in and ready to go when it was cancelled.
SpaceX said in a Tweet: ‘Standing down from launch today due to unfavourable weather in the flight path. Our next launch opportunity is Saturday, May 30 at 3:22 p.m. EDT, or 19:22 UTC.’
Hurley said: ‘We could see some raindrops on the windows and just figured that whatever it was, was too close to the launch pad at the time we needed it not to be.
‘Understand that everybody´s probably a little bit bummed out. That´s just part of the deal. … We’ll do it again, I think, on Saturday.’
Elon Musk wearing a face mask with the SpaceX logo at Cape Canaveral on Wednesday
British astronaut Tim Peake also took to Twitter to express his disappointment that the launch did not take place, but said viewers could still watch the night sky for the International Space Station.
The rocket was expected to pass across the UK sky from the West on Wednesday, and on the right side of the moon – but this view has been changed due to the movement of the Earth’s axis.
The SpaceX demo-2 mission will see the Falcon 9 rocket and attached Crew Dragon capsule shoot into space as part of NASA’s Commercial Crew Program.
If successful, it will pave the way for future partnerships between NASA and commercial companies, and a new age of space travel.
The launch is the latest in a surge of exciting sightings in the UK’s night skies.
On May 7 Britons were able to view the third supermoon of the year, where the moon appears six per cent larger than normal.
The change in appearance happened as its orbit is not entirely circular, meaning it sometimes appears closer and sometimes appears further away than normal.
The launchpad at Cape Canaveral is pictured above. The rocket will lift off 8.22pm UK time
The Falcon 9 will take off from Cape Canaveral on the other side of the Atlantic and be visible in the UK sky about 20 minutes later
Earlier this month the final supermoon of the year graced the skies. It is pictured above overshadowing Poolbeg Lighthouse in Dublin Bay, Ireland
And last month Mars, Saturn and Jupiter all appeared to align in the sky above a waning pink moon.
The juxtaposed planets – which are separated by millions of miles – remained in formation for almost a week.
However, their orbits then caused the three planets to separate. They will not appear aligned again until 2022.
The juxtaposition – the closest three planets will appear until 2022 – was captured over the village of Cobham in Gravesham, Kent.