Astronomers spotted an asteroid just hours before it impacted with Earth this morning (November 19, 2022), near Lake Erie. This is not the first time this year astronomers have discovered a rock from space just hours before it hit Earth.

Comment: When it's that small, it's a meteor, not an 'asteroid'.

But this time, it impacted over a populated area, crossing the skies of Toronto, Canada. So we have video and witnesses who said they saw, heard and felt the impact.

Ye Quanzhi, a University of Maryland astronomer who studies asteroids, comets and meteors, reported on Twitter at 1:13 a.m. EST on November 19:
Looks like a space rock is going to fall into Lake Erie area in ~2 hours (about 3:30 am EST)
He shared the link for NASA's Center for Near Earth Object Studies Hazard Assessment page. The object, C8FF042, is now removed from the page because it has struck Earth and is therefore no longer a threat.

Precise prediction

At 2:29 a.m. EST, Richard Moissl tweeted that the asteroid should impact around 8:26 UTC, which translates to 3:26 a.m. EST. That turned out to be incredibly accurate, as cameras around Toronto captured the bolide at 3:25 and 3:26 a.m. The CN Tower cam in Toronto was one of the cameras that saw the asteroid's nearly horizontal entry.

Witnesses to the asteroid

Fortunately, the space rock was less than a meter in size. Impact should have been around Brantford, Ontario. That's north of Lake Erie, west of Buffalo, NY, east of Detroit and southwest of Toronto. With such a populated area, many people had the chance to see the fireball entry into the atmosphere. People on twitter reported seeing the bright flash of light, along with the sound of atmospheric entry and even shaking, probably from the sonic boom. Twitter user @TimsDoubleD said:
I heard it and felt it almost like my house moved. Thought a generator exploded nearby.
Twitter user @SchefflerKen said:
This would have been interesting to see, but at least I got to hear it. I had for some reason woken up and a few seconds later the house cracked as it does when hit by a gust of wind and then there was a muffled rumble for two or three seconds.
Some observers reported the fireball at magnitude -10 to -20.

Those few hours of lead time were enough that some were able to capture C8FF042 with telescopes.

Asteroid hit Canada now named 2022 WJ1

David Rankin discovered asteroid C8FF042, which the Minor Planet Center has since named WJ1. The information about the newly discovered asteroid circulated on the Minor Planet Mailing List (MPML). It said:
Bill Gray has the impact point at 19 Nov 2022 8:26:54.47 UTC, lat +43.12309, lon W80.26416, which is directly over Brantford, Ontario, Canada.
Sam Deen on the MPML said:
The object will have a very grazing impact of just 10-12 degrees or so, and should be travelling WSW To ENE between Detroit and Buffalo. We should probably expect a pretty spectacular light show, considering the low angle and high population of the area.
More views from Twitter