In Larry Niven & Jerry Pournelle’s classic 1977 novel “Lucifer’s Hammer”, the Earth is struck by a large comet, killing millions and nearly wiping out civilization. In the book, a scientist explaining what a comet is made of likens it to a hot fudge sundae, which leads to the quip “Hot Fudge Sundae, which falls on a Tuesdae” meaning the day the Hammer would fall.

For Jupiter, Hot Fudge Sundae fell on a Saturdae, July 16, 1994 when fragment A of Comet Shoemaker-Levy 9 struck. The hammer blows continued alphabetically until fragment W hit the following Fridae.

Info on what SL 9 was like before it broke into fragments is pretty sketchy, but it is estimated to have been in the range of 1 to 6 miles wide until it got too close to Jupiter. Tidal forces shattered it into 21 pieces as big as (rough estimate again) 1/2 to 2 miles in size.

Gradually those fragments formed into a chain 500,000 miles long aimed at the massive planet. For six days, Jupiter was pounded by impacts that left dark patches thousands of miles wide and shot debris far out into space. Cometfall was so catastrophic that after-effects could still be seen a year later.

[Edit] Drat, If I’d thought to call it “Hot Fudge Shatterday” I could have roped Harlan Ellison’s name in too for a three-author hat-trick.