We didn’t die from 2023 BU, but why did we only find out about the asteroid on Saturday?

DART’s not much use when the asteroid is already here.

This view from NASA’s Scout system shows the deflection of asteroid 2023 BU’s trajectory – in red – caused by Earth’s gravity. The orbit of geosynchronous satellites is shown in green, and the orbit of the Moon is depicted by the gray oval. Credits: NASA/JPL-Caltech