The British will be able to see a rocket fire through the sky at 10:15 pm – as it spins around the Earth two hours after taking off from America.
Falcon 9, the first manned space flight to leave the U.S. for nine years, is scheduled to take off from Cape Canaveral, Florida, at 8:22 pm (local time).
It will then travel through the International Space Station and pass low along the southwestern horizon of the United Kingdom.
Elon Musk's historic SpaceX space flight will mark the first time that a private company will place astronauts in space.
It is the second launch attempt after Wednesday's flight was aborted because storm Bertha had arrived from the Gulf of Mexico, obstructing the flight path.
This map shows the difficult path the spacecraft is expected to travel across the UK sky tonight, as the launch progresses. In the photo on the left is the Crew Dragon spacecraft
The route that the probe is expected to take over Europe is shown above. Will be visible in the southwestern part of the British night sky
NASA and SpaceX are preparing to send two American astronauts to the International Space Station aboard an American rocket
NASA astronauts Robert Behnken and Douglas Hurley were tied up in the Crew Dragon Capsule cabin, ready to take off when the launch was canceled on Wednesday
The rocket is expected to fly low over the southwest horizon and pass the left side of the moon before disappearing.
It will appear as a small bright spot while shooting across the night sky after sunset at 9.05 pm.
The Met office predicted clear skies for most of the UK on Saturday night, making it easier to locate the rocket.
A spokesman told MailOnline: & # 39; After a hot and sunny day on Saturday, much of the UK can expect clear skies on Saturday night, with perhaps a small low cloud developing along the border coast. Scots and Northumberland in the late evening.
The British can also watch the launch, as it happens on the NASA TV channel, which is broadcast on YouTube.
The mission was canceled when storm Bertha entered the area. Pictured above is the rocket on Wednesday just before the launch was canceled
Wednesday's launch was canceled because bad weather meant that the launch had to be delayed for a few seconds – meaning it would lose its trajectory to the ISS, in rapid motion.
NASA astronauts, Bob Behnken and Doug Hurley, were stuck and ready to go when it was canceled.
SpaceX said in a Tweet: & # 39; Stop being launched today due to the unfavorable weather on the flight path. Our next launch opportunity is Saturday, May 30 at 3:22 pm. EDT or 19:22 UTC. & # 39;
Hurley said: “We were able to see a few drops of rain on the windows and imagined that, whatever it was, it was very close to the launch pad at the time we needed it not to be.
& # 39; Understand that everyone is probably a little upset. This is only part of the agreement. I think we will do it again on Saturday.
Elon Musk wearing a face mask with the SpaceX logo in 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 from 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 that view has been altered due to the movement of the Earth's axis.
The SpaceX demo-2 mission will see the Falcon 9 rocket and the Crew Dragon capsule attached to 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 era of space travel.
The launch is the latest in a series of exciting sightings in the UK's night skies.
On May 7, the British were able to watch the third supermoon of the year, where the moon appears six percent larger than normal.
The change in appearance came about because its orbit is not entirely circular, which means that it sometimes appears closer and at other times more distant than normal.
The launch bar at Cape Canaveral is shown above. The rocket will take off at 8:22 pm, UK time
Falcon 9 will take off from Cape Canaveral, across the Atlantic, and will be visible in the UK sky about 20 minutes later
Earlier this month, the end of the year supermoon graced the skies. Photographed above is dazzling Poolbeg Lighthouse in Dublin Bay, Ireland.
And last month, Mars, Saturn and Jupiter seemed to line up in the sky above a waning pink moon.
The juxtaposed planets – which are separated by millions of kilometers – remained in formation for almost a week.
However, their orbits caused the three planets to separate. They will not appear aligned again until 2022.
The juxtaposition – the three closest planets will appear by 2022 – was captured over the village of Cobham, in Gravesham, Kent.