An asteroid more than a mile wide skimmed past Earth on Wednesday, hurtling through space at a speed of around 19,000 miles per hour.
The rock, known as (52768) 1998 OR2, was just 3.9 million miles away, around 16 times the distance between the Earth and the Moon, when it made its closest approach at around 11am BST.
The flyby was confirmed on Twitter by the South African Astronomical Observatory, which described the object as “one of the largest potentially hazardous asteroids known to exist”.
Although the asteroid was not expected to collide with the planet, Dr Brad Tucker, an astrophysicist at the Australian National University, described it as “smaller than the asteroid that impacted the Earth and wiped out the dinosaurs”.
But scientists decided to classify it as a potentially hazardous object (PHO) because of its size and the fact that it came 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 space 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 13, joked that the most recent pictures of the asteroid made it look as though it was 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.”
The asteroid orbits the Sun once every three years and eight months and was first spotted by Nasa in 1998.