Why the chance of an asteroid hitting Earth in 2032 keeps changing

An asteroid has a slight chance of hitting Earth in 2032. Here's why the odds are a moving target, according to the astronomer who invented the scale used to measure such risks.

An asteroid that will fly near Earth in 2032 is now expected to pass safely by the planet, with the probability of impact just 0.004%, NASA said on Monday.

That is a significant downgrade in risk from the record high chance of collision that the space agency gave early last week, when it put the odds at 3.1%, or 1 in 32.

The asteroid, known as 2024 YR4, is between 130 and 300 feet wide — big enough to cause local damage if it were to hit Earth. But the precise odds of that happening have been a moving target since the space rock was first detected roughly two months ago.

The very slim chance NASA estimated on Monday was even smaller than the 0.28% probability it gave late last week. Just days earlier, the agency had put the probability at 1.5%, and before that at 3.1%.

The brief time the odds exceeded 3% made the space rock the first object to officially be classified as a Level 3 out of 10 in a measurement known as the Torino scale, which astronomer Richard Binzel first proposed nearly three decades ago.

https://www.nbcnews.com/science/space/asteroid-hit-earth-why-chances-keep-changing-rcna192723

---