A major asteroid capable of destroying a city just blasted past Earth, and scientists didn’t see it until a day later. The asteroid, 2017 VL2, is about the size of a whale and passed a mere 73,000 miles from the Earth, or about a third of the distance between the Earth and the moon.

Asteroid 2017 VL2, which stretches between 52 and 105 feet in diameter and could destroy all life within a 3.7 mile radius if it had struck the Earth, was spotted on Nov. 10, whereas it reached its closest point to Earth on Nov. 9. The space rock will come back into Earth’s general neighborhood in 2125, and is part of the Apollo asteroids first describes in the 1930s.

NASA astronomers spotted asteroid 2017 VL2 using the Mauna Loa observatory in Hawaii. NASA has even set up an office dedicated to detecting asteroids like this, but it’s still hard to find every single one, and many times such space rocks pass by undetected – or worse, strike the Earth and causes damage like the one that hit Chelyabinsk, Russia, in 2013.