Comet Shoemaker–Levy 9 in precovery images obtained before March 24, including Kin Endate from a photograph exposed on March 15, S. Otomo on March 17, and a team led by Eleanor Helin from images on March 19. No precovery images dating back to earlier than March 1993 have been found. Before the comet was captured by Jupiter, it was probably a short-period comet with an aphelion just inside Jupiter's orbit, and a perihelion interior to the asteroid belt. The volume of space within which an object can be said to orbit Jupiter is defined by Jupiter's Hill sphere (also called the Roche sphere).
Lexell's Comet The comet was also noted by several other astronomers. The comet was observed in Japan. Surviving records identify it as an astronomical and historical phenomenon. It was observed in the Hejaz in Safar 1184 AH (June 1770), where some believed it to be the comet predicted by the poet al-Fasi, portending future events. On July 1, 1770, the comet passed 0.015 astronomical units from Earth, or approximately 6 times the radius of the Moon's orbit. Charles Messier measured the coma as 2° 23' across, around four times the apparent angular size of the Moon. An English astronomer at the time