Janus is an inner satellite of Saturn. It is also known as Saturn X. It is named after the mythological Janus.
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery, identified through its various designations, and the discoverer(s) listed.
Charles Thomas Kowal was an American astronomer known for his observations and discoveries in the Solar System. As a staff astronomer at Caltech's Mount Wilson and Palomar Mountain observatories between 1961 and 1984, he found the first of a new class of Solar System objects, the centaurs, discovered two moons of the planet Jupiter, and discovered or co-discovered a number of asteroids, comets and supernovae. He was awarded the James Craig Watson Medal for his contributions to astronomy in 1979.
Comet Boethin was a periodic Jupiter-family comet discovered in 1975 by Leo Boethin. It appeared again in January 1986 as expected. Although the comet was next expected at perihelion in April 1997, no observations were reported, and the comet is thought to have disintegrated. It has not been observed since March 1986. The comet might have come to perihelion in late July 2020, but the uncertainty in the comet's position is hundreds of millions of km. The old orbit would have the comet next coming to perihelion around November 2031.
77P/Longmore is a periodic comet in the Solar System, with a period of 6.8 years.
78P/Gehrels, also known as Gehrels 2, is a Jupiter-family periodic comet in the Solar System with a current orbital period of 7.22 years.
Comet Schaumasse is a periodic comet discovered by Alexandre Schaumasse on 1 December 1911 as 12th magnitude. It next comes to perihelion on 8 January 2026 and should brighten to about magnitude 9.
54P/de Vico–Swift–NEAT is a periodic comet in the Solar System first discovered by Father Francesco de Vico on August 23, 1844. It has become a lost comet several times after its discovery. The comet makes many close approaches to Jupiter. The comet was last observed on 20 December 2009 by Ageo Observatory.
1916 Boreas, provisional designation 1953 RA, is an eccentric, stony asteroid and near-Earth object of the Amor group, approximately 3 kilometers in diameter. After its discovery in 1953, it became a lost asteroid until 1974. It was named after Boreas from Greek mythology.
1877 Marsden, provisional designation 1971 FC, is a carbonaceous Hildian asteroid from the outermost region of the asteroid belt, approximately 35 kilometers in diameter. It was discovered during the Palomar–Leiden Trojan survey in 1971, and named after British astronomer Brian Marsden.
A minor planet is "lost" when today's observers cannot find it, because its location is too uncertain to target observations. This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observation arc for the object is too short, or too few observations were made before the object became unobservable.
122P/de Vico is a periodic comet with an orbital period of 74 years. It fits the classical definition of a Halley-type comet with. It was discovered by Francesco de Vico in Rome on February 20, 1846.
Comet Arend or 50P/Arend is a periodic comet in the Solar System which was discovered on October 4, 1951. It was discovered by astronomer Sylvain Julien Victor Arend at the Royal Observatory of Belgium located in the municipality of Uccle. The comet was illustrated at approximately a magnitude of 14 and also exhibited a nucleus within a coma 14 arc seconds across. From its discovery, the comet has had 7 perihelions with its last return of Earth recorded on November 1, 2007. The comet's next perihelion will be in the year 2024.
Comet Swift–Tuttle is a large periodic comet with a 1995 (osculating) orbital period of 133 years that is in a 1:11 orbital resonance with Jupiter. It fits the classical definition of a Halley-type comet, which has an orbital period between 20 and 200 years. The comet was independently discovered by Lewis Swift on July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862.
163P/NEAT is a periodic comet discovered on November 5, 2004 by Near-Earth Asteroid Tracking (NEAT) using the 1.2 meter Samuel Oschin telescope at Palomar Observatory.
6250 Saekohayashi, provisional designation 1991 VX1, is a bright Hungaria asteroid and relatively slow rotator from the inner regions of the asteroid belt, approximately 3.7 kilometers in diameter. It was discovered on 2 November 1991, by American astronomer Eleanor Helin at Palomar Observatory in California, and later named after Japanese astronomer Saeko Hayashi.
104P/Kowal, also known as Kowal 2, is a periodic Jupiter-family comet discovered by Charles T. Kowal in 1979. The orbit was confirmed after new sightings in 1991 and 1998.
108P/Ciffréo is a periodic comet with an orbital period of 7 years discovered by Jacqueline Ciffréo on November 8, 1985. The comet is noted for having a peculiar double morphology, in which the nucleus is accompanied by a comoving, detached, diffuse tail, which is probably a perspective artifact of particles ejected sunwards and then repelled by solar wind.
126P/IRAS is a periodic comet with an orbital period of 13.4 years. It was discovered in images taken by the Infrared Astronomical Satellite (IRAS) on 28 July 1983 by J. Davies. The discovery was confirmed with images taken with the 1.2-m Schmidt telescope at Palomar Observatory.
210P/Christensen is a Jupiter family periodic comet with an orbital period of 5.7 years. It was discovered by Eric J. Christensen on 26 May 2003 in images taken by the Catalina Sky Survey and recovered in images obtained by STEREO, the first time a single-apparition comet was recovered by a spacecraft.
