Scientists say a 30m-wide (100ft) asteroid will pass between the moon and Earth later, providing spectacular views for anyone with a good telescope.
The space rock called 2014 DX110 is the length of three double-decker buses and will come within 214,745 miles (346,599km) of the planet at around 9pm UK time.
It will be moving at 33,000mph (53,108kph).
Nasa’s Jet Propulsion Laboratory has been monitoring its flight and classifies it as one of a number of Apollo-class asteroids, which cross the Earth’s orbit.
The Chelyabinsk asteroid which exploded over the Russian region last year was also Apollo-class.
Professor Tim O’Brien, from the University of Manchester’s Jodrell Bank Observatory, said: “There is an incredibly tiny chance of 2014 DX110 getting closer to Earth but everything indicates that it’s nothing to worry about.
“This asteroid was only spotted last month and we now know there are many more like it that are, as yet, undetected.
“The Chelyabinsk meteor event was a reminder of the damage these things can do so it’s important to keep monitoring and looking for them.
“On a comforting note though, it’s good to remember that there are many more smaller, and harmless objects, than large ones out there.”
Scientists say the rock will be too faint to see with the naked eye but should be visible with a reasonably sized telescope.
Astronomers will also need to work out exactly where it will cross the night sky, so more experienced stargazers might have a better chance of spotting it.