A small asteroid, termed a city-killer, surprised astronomers by passing by yesterday, quite closely. From All-Sky Automated Survey (ASAS):
This is the video of the close encounter of Asteroid 2019 OK we have been Twitting all day with the Earth: https://t.co/bjT7uhQJuO pic.twitter.com/3e4UyPcdPl
— ASAS-SN (@SuperASASSN) July 25, 2019
ASAS seems more interested in supernovae, but I think a hit from this asteroid would have been bright even for them. From WaPo:
[Alan Duffy of the Royal Institution of Australia] said astronomers have a nickname for the kind of space rock that just came so close to Earth: “City-killer asteroids.” If the asteroid had struck Earth, most of it would have probably reached the ground, resulting in devastating damage, Brown said.
“It would have gone off like a very large nuclear weapon” with enough force to destroy a city, he said. “Many megatons, perhaps in the ballpark of 10 megatons of TNT, so something not to be messed with.”
In 2013, a significantly smaller meteor — about 20 meters (65 feet) across, or the size of a six-story building — broke up over the Russian city of Chelyabinsk and unleashed an intense shock wave that collapsed roofs, shattered windows and left about 1,200 people injured. The last space rock to strike Earth similar in size to Asteroid 2019 OK was more than a century ago, Brown said. That asteroid, known as the Tunguska event, caused an explosion that leveled 2,000 square kilometers (770 square miles) of forest land in Siberia.
Another reason – and counting – to support efforts to detect NEOs, Near Earth Objects, before they end up hitting us.
