Mysterious black spot appears on Jupiter

A black spot wider than the Earth suddenly appeared on Jupiter this week.  An amateur astronomer was the first to spot the blotch (visible on the top of the image):

Post-slashdotted site here.

So what is it?  Could it be another large, fast object striking the gas giant, a la Shoemaker-Levy, fourteen years ago this month?

Comments

[HP]

Could it be another large, fast object striking the gas giant?

Yup.

[Bryan Alexander]

Thanks, HP. Just posted anew, springing from (and crediting) yourself.