Linus, formal designation (22) Kalliope I, is an

asteroid moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

that orbits the large

M-type asteroid M-type (metallic-type, aka M-class) asteroids are a spectral class of asteroids which appear to contain higher concentrations of metal phases (e.g. iron-nickel) than other asteroid classes, and are widely thought to be the source of iron meteorit ...

22 Kalliope 22 Kalliope (; ) is a large M-type asteroid from the asteroid belt discovered by J. R. Hind on 16 November 1852. It is named after Calliope, the Greek Muse of epic poetry. It is orbited by a small moon named Linus. Characteristics Kalliope i ...

. It was discovered on August 29, 2001, by

astronomers An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, moons, comets and galaxies – in either observ ...

Jean-Luc Margot Jean-Luc Margot (born 1969) is a Belgian-born astronomer and a UCLA professor with expertise in planetary sciences and SETI. Career Margot has discovered and studied several binary asteroids with radar and optical telescopes. His discoveries ...

and Michael E. Brown with the

Keck telescope The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and, when c ...

, in

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

. Another team also detected the moon with the Canada-France-Hawaii Telescope on September 2, 2001. Both telescopes are on

Mauna Kea Mauna Kea (, ; abbreviation for ''Mauna a Wākea''); is a dormant Shield volcano, shield volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in Hawaii a ...

. It received the provisional designation S/2001 (22) 1, until it was named. The naming proposal appeared in the discovery paper and was approved by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

in July 2003. Although the naming proposal referred to the mythological Linus, son of the muse

Calliope In Greek mythology, Calliope ( ; ) is the Muse who presides over eloquence and epic poetry; so called from the ecstatic harmony of her voice. Hesiod and Ovid called her the "Chief of all Muses". Mythology Calliope had two famous sons, OrpheusH ...

and the inventor of melody and rhythm, the name was also meant to honor

Linus Torvalds Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish software engineer who is the creator and lead developer of the Linux kernel. He also created the distributed version control system Git. He was honored, along with Shinya Yam ...

, inventor of the

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

operating system kernel, and Linus van Pelt, a character in the ''

Peanuts ''Peanuts'' (briefly subtitled ''featuring Good ol' Charlie Brown'') is a print syndication, syndicated daily strip, daily and Sunday strip, Sunday American comic strip written and illustrated by Charles M. Schulz. The strip's original run ext ...

'' comic strip. With an estimated (17 ± 1 mi) diameter, Linus is very large compared to most asteroid moons, and would be a sizable asteroid by itself. The only known larger moons in the

main belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

are the smaller components of the double asteroids

617 Patroclus 617 Patroclus ( ) is a large binary Jupiter trojan asteroid. It is a dark D-type asteroid and a List of slow rotators (minor planets), slow rotator, due to the 103-hour orbital period of its two components. It is one of five Jupiter trojan aster ...

and

90 Antiope 90 Antiope is a double asteroid in the outer asteroid belt. It was discovered on 1 October 1866, by Karl Theodor Robert Luther, Robert Luther. In 2000, it was found to consist of two almost-equally-sized bodies orbiting each other. At average d ...

. It has been estimated that Linus' orbit precesses at quite a rapid rate, making one cycle in several years. This is attributed primarily to the non-spherical shape of Kalliope. Linus's brightness has varied appreciably between observations, which may indicate that its shape is elongated. Linus may have formed out of

impact Impact may refer to: * Impact (mechanics), a large force or mechanical shock over a short period of time * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Imp ...

ejecta Ejecta (; ) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic rock, pyroclastic materials (tephra) that came out of a explosive eruption, volcanic explosion and magma eruption v ...

from a

collision In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great for ...

with Kalliope, or a fragment captured after disruption of a parent asteroid (a proto-Kalliope).

References

External links

IAUC 7703: S/2001 (22) 1
announcing Linus' discovery (2001 September 3)

announcing Linus' naming (2003 August 8)

* ttps://web.archive.org/web/20060128034217/http://astron.berkeley.edu/~fmarchis/Science/Asteroids/#Kalliope Kalliope and Linusvery well resolved with the 8m VLT
orbit diagram for Linus
{{Small Solar System bodies Asteroid satellites Discoveries by Michael E. Brown