PARIS: The chances have plummeted that a newly-discovered asteroid with the potential to wipe out a city will hit Earth on Valentine’s Day 2046, the European Space Agency said on Tuesday.

The asteroid, which is named 2023 DW and is estimated to be around the size of a 50-metre Olympic swimming pool, was first spotted by a small Chilean observatory on Feb 26.

It swiftly shot to the top of Nasa and ESA lists of asteroids that pose a danger to Earth, leading to a raft of alarming news headlines, some warning lovers to cancel their Valentine’s plans on Feb 14, 2046.

Late last month the asteroid was given a one in 847 chance of hitting Earth — but the odds rose to one in 432 on Sunday, according to the ESA’s risk list. However Richard Moissl, the head of the ESA’s planetary defence office, said on Tuesday that overnight the probability fell to one in 1,584.

“It will go down now with every observation until it reaches zero in a couple of days at the latest,” he said. “No one needs to be worried about this guy.” Nasa on Tuesday lowered its own odds of impact to one in 770, meaning there was a 99.87 per cent chance that the asteroid will miss Earth.

“We tend to be a little more conservative, but it definitely appears to now have a downward trend in probability,” Nasa’s planetary defence officer Lindley Johnson said. He said it was normal for the impact odds of newly discovered asteroids to briefly rise before rapidly falling.

This is because new observations shrink the “uncertainty region” where the asteroid will travel to on its closest point to Earth, he said.

While the Earth is still inside that uncertainty region, the odds temporarily increase -- until further observations exclude Earth and the probability drops down to zero, as is expected to happen with 2023 DW.

What if it does hit Earth?

But what would happen in the increasingly unlikely event that the asteroid does strike Earth? Davide Farnocchia, a scientist at Nasa’s Centre for Near-Earth Object Studies, said a good comparison was the Tunguska event, in which a similarly-sized asteroid is believed to have exploded in the atmosphere above a sparsely populated area in Siberia in 1908. “The resulting explosion flattened trees over an area of about 2,000 square kilometres,” Farnocchia said. London covers an area of around 1,600 square kilometres.

Moissl said that an asteroid the size of 2023 DW would create “regionalised destruction” and not have a major effect on the rest of the world.

The asteroid, which is orbiting the Sun, came around nine million kilometres from Earth during its most recent closest approach on Feb 18 — a week before it was discovered. If it was to strike Earth in 2046, it would be speeding along at around 15 kilometres (nine miles) a second, according to estimations.

Published in Dawn, March 15th, 2023