http://www.youtube.com/watch?v=jIkr86xKcwQ&feature=player_embedded

For the second time this summer, amateur astronomers recorded an impact on Jupiter big enough to be seen from earth. Astronomer Masayuki Tachikawa of Japan was able to take the video early Saturday morning, and the impact was quickly confirmed by other astronomers. According to Sky & Telescope, neither Chris Go nor Anthony Wesley, the two amateurs who witnessed the June 3 impact, were watching the planet on Saturday.

I bet impacts of that scale happen all the time. Jupiter makes for a pretty big gravity "well", and there is a lot of junk floating out there.

I wonder what the size of the asteroid is? Given the optical flash was visible on earth, using an amateur (although big $$$) telescope, it mustof been a doozy.

Bryan

It's a good thing that we have this celestial mosquito trap at the gates of the inner Solar System; and a good thing that these events are observed - it should encourage funding for defence against NEOs (Near Earth Objects). Some of these little Jupiter flashes might rate a 10 on The Torino Impact Hazard Scale:
http://neo.jpl.nasa.gov/torino_scale.html