Experts unaware of 'city-killer' asteroid that just missed Earth

MIAMI – So an asteroid that could obliterate a major city passed super close to Earth on Thursday and experts knew nothing about it.

(Gulp)

Although a couple other asteroids were predicted to zoom by the planet this week, Asteroid 2019 OK was an unexpected visitor that passed about 45,360 miles from Earth, roughly one-fifth the distance to the moon, according to the Washington Post.

The asteroid measured nearly 110 yards wide, which is not large but could do a considerable amount of damage to a city.

"It would have gone off like a very large nuclear weapon" with enough force to destroy a city, said Alan Duffy of the Royal Institution of Australia. "Many megatons, perhaps in the ballpark of 10 megatons of TNT, so something not to be messed with."

And all the while, most scientists were unaware the asteroid existed.

"It snuck up on us pretty quickly," said Michael Brown, an associate professor with Australia's Monash University. "People are only sort of realizing what happened pretty much after it's already flung past us."

Teams in the U.S. and Brazil discovered 2019 OK earlier in the week, but the information was released just before it flew by.

Smaller asteroids like 2019 OK are difficult to detect, unlike the nearly 90 percent of asteroids that are a kilometer are larger. Nearly 90 percent of the larger asteroids have been identified.

"It should worry us all quite frankly," said Alan Duffy of the Royal Institution of Australia. "It's not a Hollywood movie. It is a clear and present danger."