Scott Sander Sheppard (born 1977) is an American astronomer and a discoverer of numerous moons, comets and minor planets in the outer Solar System.
He is an astronomer in the Department of Terrestrial Magnetism at the Carnegie Institution for Science in Washington, DC. He attended Oberlin College as an undergraduate, and received his bachelor in physics with honors in 1998. Starting as a graduate student at the Institute for Astronomy at the University of Hawaiʻi at Mānoa, he was credited with the discovery of many small moons of Jupiter, Saturn, Uranus, and Neptune. He has also discovered the first known trailing Neptune trojan,, the first named leading Neptune trojan, 385571 Otrera, and the first high inclination Neptune trojan, . These discoveries showed that the Neptune trojan objects are mostly on highly inclined orbits and thus likely captured small bodies from elsewhere in the Solar System.
The main-belt asteroid 17898 Scottsheppard, discovered by LONEOS at Anderson Mesa Station in 1999, was named in his honor.
| + Minor planets discovered: 23 | ||
| 15 February 1999 | ||
| 9 December 2001 | ||
| 9 December 2001 | ||
| 11 December 2001 | ||
| 9 December 2001 | ||
| 2 April 2000 | ||
| 9 December 2001 | ||
| 14 October 2007 | ||
| 16 October 2004 | ||
| 8 October 2005 | ||
| 10 December 2001 | ||
| 9 December 2001 | ||
| 13 March 2010 | ||
| 21 April 2010 | ||
| 17 March 2013 | ||
| 31 March 2000 | ||
| 16 March 2013 | ||
| 16 March 2013 | ||
| 24 March 2014 | ||
| 10 December 2001 | ||
| 10 December 2001 | ||
| 17 March 2013 | ||
| 17 March 2013 | ||
| 13 October 2015 | ||
| 13 August 2021 | ||
| 13 January 2022 | [1] | |
with J. X. Luu with D. C. Jewitt with Chadwick Trujillo with J. T. Kleyna with A. Udalski with M. Kubiak with R. Poleski with D. J. Tholen |
Sheppard was the lead discoverer of the object with the most distant orbit known in the Solar System, (nicknamed Biden). In 2014, the similarity of the orbit of to other extreme Kuiper belt object orbits led Sheppard and Trujillo to propose that an unknown Super-Earth mass planet (2–15 Earth masses) in the outermost Solar System beyond 200 AU and up to 1500 AU is shepherding these smaller bodies into similar orbits (see Planet X or Planet Nine). The extreme trans-Neptunian objects and, announced in 2016 and co-discovered by Sheppard, further show a likely unknown massive planet exists beyond a few hundred AU in the Solar System, with being the first known high semi-major axis and high perihelion object anti-aligned with the other known extreme objects. In 2018, the announcement of the high perihelion inner Oort cloud object 541132 Leleākūhonua (nicknamed "The Goblin") by Sheppard et al., being only the third known after and Sedna, further demonstrated that a super-Earth planet in the distant solar system likely exists as Leleākūhonua has many orbital similarities as the two other known inner Oort cloud objects.
Sheppard has been involved in the discovery of many small Solar System bodies such as trans-Neptunian objects, centaurs, comets and near-Earth objects.