Discovery of a Possible Impact SPOT on Jupiter Recorded in 1690

Upon surveying old drawings stored in libraries we discovered a dark spot drawn by G. Cassini in 1690 December. The size and visibility of this spot were similar to those produced by the impacts of Comet D/Shoemaker-Levy 9 in 1994. During the 18 d observational period, this spot was stretched mainly in the east--west direction by a zonal wind. Considering this circumstantial evidence together with a result of simple simulation of the time variation, we conclude that this spot was possibly produced by the impact of a single astronomical object around 1690 December 5.