, also written as (79360) 1997 CS29, is a double

Double planet

In astronomy, double planet and binary planet are informal terms used to describe a binary system of two astronomical objects that each satisfy the definition of planet and that are near enough to each other to have a significant gravitational effect on each other compared with the effect of the...

 cubewano

Cubewano

A classical Kuiper belt object, also called a cubewano is a low-eccentricity Kuiper belt object that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune’s orbit...

. It was discovered on February 3, 1997 by Jane X. Luu, David C. Jewitt

David C. Jewitt

David C. Jewitt is a professor of astronomy formerly at the University of Hawaii Institute for Astronomy, now at UCLA. He was born in 1958 in England, and is a 1979 graduate of the University of London. Jewitt received an M.Sc. and a Ph.D. in astronomy at the California Institute of Technology in...

, Chad Trujillo

Chad Trujillo

Chadwick A. "Chad" Trujillo is an astronomer and the co-discoverer of the dwarf planet Eris.Trujillo works with computer software and has examined the orbits of the numerous trans-Neptunian objects , which is the outer area of the solar system that he specialized in. In late August 2005, it was...

, and Jun Chen

Jun Chen

Jun Chen is a Chinese American astronomer.She obtained her BS at Beijing University in 1990, and obtained her Ph.D. from the University of Hawaii in 1997....

 at the Mauna Kea Observatory

Mauna Kea Observatory

The Observatories at Mauna Kea, , are an independent collection of astronomical research facilities located on the summit of Mauna Kea on the Big Island of Hawai'i, USA. The facilities are located in a special land use zone known as the "Astronomy Precinct," which is located in the Mauna Kea...

, Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

.

Orbit

1997 CS29 is a dynamically cold classical object (cubewano). It orbits very close to 7:4 mean motion resonance with Neptune

Neptune

Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...

.

Physical characteristics

In 2010 thermal flux from 1997 CS29 in the far-infrared was measured by the Herschel Space Telescope. As a result its equivalent (assuming that it is a singular body) size was estimated to lie within a range from 250 to 420 km.

1997 CS29 is very red in the visible and has a flat featureless spectrum in the near-infrared. There is no water ice absorption bands in its near-infrared spectrum, which resembles that of Ixion

28978 Ixion

28978 Ixion is a Kuiper belt object discovered on May 22, 2001. Ixion is a plutino and a very likely dwarf planet; its diameter of 650 km estimated by Spitzer makes it about the fifth largest plutino. It is named after Ixion, a figure from Greek mythology...

.

Natural satellite

has one known natural satellite

Asteroid moon

A minor planet moon is an astronomical body that orbits a minor planet as its natural satellite. It is thought that many asteroids and Kuiper belt objects may possess moons, in some cases quite substantial in size...

, which, however, is so close to the size of its primary that the two may be better thought of as a double cubewano.

S/2005 (79360) 1

The images of 1997 CS29 and its satellite, S/2005 (79360) 1 were resolved in Hubble Space Telescope

Hubble Space Telescope

The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 observations of 22 October 2002 and was discovered by Denise C. Stephens and Keith S. Noll, who announced the satellite on 5 October 2005. It orbits at about 2300 km, taking about 6 day

Day

A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...

s to complete one orbit. It is about 292 km in diameter, nearly as large as .