Yesterday, an amateur astronomer noticed that a large black spot had appeared near Jupiter's Southern pole. These first pictures of the phenomenon are prompting many to speculate that a passing comet or asteroid struck the gas giant.

Anthony Wesley reports that he noticed the spot (seen at the top of the photo above) while observing Jupiter yesterday from his home observatory near Murrumbateman in New South Wales, Australia. Wesley, who had observed the planet two days earlier but had not seen the black spot, speculates that the spot might be an impact spot, possible the result of a comet or asteroid strike.

And, while Phil Plait, Bad Astronomy blogger and author of Death from the Skies!, initially cautioned excited armchair astronomers that the spot might be a mere weather event, he agrees that the emerging data seems to point to an actual impact.

Impact Mark on Jupiter