An asteroid more than a mile wide will skim past Earth on Wednesday while travelling at a speed of around 19,000 miles per hour (30,578 km/h).
The space rock, known as (52768) 1998 OR2, is expected to make its closest approach at 10.56am BST, when it will be just 3.9 million miles (6.3m km) away — around 16 times the distance between the Earth and the Moon.
Although the asteroid is classified as a potentially hazardous object (PHO), scientists have said it will not put the planet at risk.
Dr Brad Tucker, an astrophysicist at the Australian National University, said: “This asteroid poses no danger to the Earth and will not hit — it is one catastrophe we won’t have.
“While it is big, it is still smaller than the asteroid that impacted the Earth and wiped out the dinosaurs.”
He said an asteroid is classed as a PHO if it is bigger than 500ft and comes within five million miles of Earth’s orbit.
Dr Anne Virkki, head of Planetary Radar at the Arecibo Observatory in Puerto Rico, who has been tracking the 1.2 mile-wide rock, said understanding more about PHOs will help “improve impact-risk mitigation technologies”.
At present, there are no known PHOs that pose an immediate danger to the Earth.
The team, who began observations on April 13th, joked that the most recent pictures of the asteroid made it look as though it is wearing a mask.
Dr Virkki said: “The small-scale topographic features such as hills and ridges on one end of asteroid 1998 OR2 are fascinating scientifically.
“But, since we are all thinking about Covid-19, these features make it look like 1998 OR2 remembered to wear a mask.”
Scientists will continue to monitor the asteroid, although the next closest approach is not expected to take place for another 49 years.
Flaviane Venditti, a research scientist at the observatory, said: “The radar measurements allow us to know more precisely where the asteroid will be in the future, including its future close approaches to Earth.
“In 2079, asteroid 1998 OR2 will pass Earth about 3.5 times closer than it will this year, so it is important to know its orbit precisely.”