Comet Shoemaker–Levy 9 then fell to below pre-impact temperatures 2–3 weeks afterwards, before rising slowly to normal temperatures. SL9 is not unique in having orbited Jupiter for a time; five comets, (including 82P/Gehrels, 147P/Kushida–Muramatsu, and 111P/Helin–Roman–Crockett) are known to have been temporarily captured by the planet. Cometary orbits around Jupiter are unstable, as they will be highly elliptical and likely to be strongly perturbed by the Sun's gravity at apojove (the furthest point on the orbit from the planet). By far the most massive planet in the Solar System, Jupiter can capture objects relatively frequently, but the size of SL9 makes it a
Comet Shoemaker–Levy 9 thus a serendipitous discovery, but one that quickly overshadowed the results from their main observing program. Comet Shoemaker–Levy 9 was the ninth periodic comet (a comet whose orbital period is 200 years or less) discovered by the Shoemakers and Levy, hence its name. It was their eleventh comet discovery overall including their discovery of two non-periodic comets, which use a different nomenclature. The discovery was announced in IAU Circular 5725 on March 27, 1993. The discovery image gave the first hint that comet Shoemaker–Levy 9 was an unusual comet, as it appeared to show multiple nuclei in an elongated region