118401 LINEAR (provisional designation 1999 RE₇₀) is an asteroid and main-belt comet (176P/LINEAR, also known as LINEAR 52) which was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) 1-metre telescopes in Socorro, New Mexico on September 7, 1999. (118401) LINEAR was discovered to be cometary on November 26, 2005, by Henry H. Hsieh and David C. Jewitt as part of the Hawaii Trails project using the Gemini North 8-m telescope on Mauna Kea and was confirmed by the University of Hawaii's 2.2-m (88-in) telescope on December 24-27, 2005, and Gemini on December 29, 2005. Based on an absolute magnitude (H) of 15.04, (118401) LINEAR is assumed to be smaller than 6 km in diameter. The Lincoln Near-Earth Asteroid Research (LINEAR) project is a cooperative project between the United States Air Force, NASA and MITs Lincoln Laboratory for the systematic discovery of near-Earth asteroids. ... September 7 is the 250th day of the year (251st in leap years). ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found. ... The Themis Asteroid Family The Themis Asteroid Family is a Hirayama family of asteroids found in the outer portion of the main asteroid belt, between the orbits of Mars and Jupiter. ... A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail â€” both primarily from the effects of solar radiation upon the comets nucleus, which itself is a minor body composed of rock, dust... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... June 14 is the 165th day of the year in the Gregorian calendar (166th in leap years), with 200 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... giga- (symbol: G) is a prefix in the SI system of units denoting 109, or 1 000 000 000. ... The metre, or meter (U.S.), is a measure of length. ... The astronomical unit (AU or au or a. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Water, Rabbit, and Deer: three of the 20 day symbols in the Aztec calendar, from the Aztec Sun Stone. ... A Julian year is the length of an average year in the Julian calendar, 365. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... Look up second in Wiktionary, the free dictionary. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The Longitude of the ascending node () is one of the orbital elements used to specify the orbit of an object in space. ... The argument of the perihelion is one of the orbital elements describing the orbit of a planet. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... For the majority of numbered asteroids, almost nothing is known apart from a few physical parameters. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... Gravity is a force of attraction that acts between bodies that have mass. ... Space Shuttle Atlantis launches on mission STS-71 In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling... 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The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail â€” both primarily from the effects of solar radiation upon the comets nucleus, which itself is a minor body composed of rock, dust... Non-periodic comets are seen only once. ... The Lincoln Near-Earth Asteroid Research (LINEAR) project is a cooperative project between the United States Air Force, NASA and MITs Lincoln Laboratory for the systematic discovery of near-Earth asteroids. ... October 18 is the 291st day of the year (292nd in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The provisional designation of comets and asteroids are similar to each other: they both follow a pattern set in 1925 by the Minor Planet Center of the IAU. Historical designations At first, astronomers strove to assign symbols to the minor planets: 1 Ceres a stylized sickle 2 Pallas a lozenge... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... November 6 is the 310th day of the year (311th in leap years) in the Gregorian Calendar, with 55 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... The astronomical unit (AU or au or a. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... October 18 is the 291st day of the year (292nd in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... June 30 is the 181st day of the year (182nd in leap years) in the Gregorian Calendar, with 184 days remaining. ... 2011 (MMXI) will be a common year starting on Saturday of the Gregorian calendar. ... 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December 29 is the 363rd day of the year (364th in leap years) in the Gregorian Calendar, with 2 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us (in the absence of interstellar extinction!). It allows the overall brightnesses of objects to be compared without regard to distance. ...

The main-belt comets are unique in that they have flat, circular, asteroid-like orbits, and not the elongated, often tilted orbits characteristic of all other comets. Since (118401) LINEAR can generate a coma (produced by vapour boiled off the comet), it must be an icy asteroid. When a typical comet approaches the Sun, its ice heats up and sublimates (changes directly from ice to gas), venting gas and dust into space, creating a tail and giving the object a fuzzy appearance. Far from the Sun, sublimation stops, and the remaining ice stays frozen until the comet's next pass close to the Sun. In contrast, objects in the asteroid belt have essentially circular orbits and are expected to be mostly baked dry of ice by their confinement to the inner solar system. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... The comet Ikeya-Zhang exhibiting a bright, condensed coma (march 2002) In astronomy, the nebulous envelope around the nucleus of a comet is called its coma (from the Latin word for hair). It is formed when the comet passes close to the sun on its highly elliptical orbit; as the... The Sun is the star of our solar system. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Sublimation has three separate meanings: Sublimation (physics), the change from solid to gas without passing the liquid state Sublimation (psychology), the transformation of emotions Dye sublimation, the transference of printed images to a synthetic substrate by the application of heat Category: ... A gas is one of the four major phases of matter (after solid and liquid, and followed by plasma, that subsequently appear as a solid material is subjected to increasingly higher temperatures. ... After just three years of use dust has blocked this laptop heat sink, making the computer unusable Dust is a general name for minute solid particles with diameters less than 500 micrometers (otherwise, see sand or granulates) and, more generally, for finely divided matter. ... Space has been an interest for philosophers and scientists for much of human history. ...

It is suggested that these main-belt asteroid-comets are evidence of a recent impact exposing an icy interior to solar radiation. A good question is, "How long will current main-belt comets keep generating a coma?" It is estimated short period comets remain active for about 10,000 years before having most of their ice sublimated away and going dormant.

References

• New Class of Comets
• Main-Belt Comets
• orbital simulation from JPL (Java)
• 118401 on November 13th, 2011
• LINEAR home page
• Seiichi Yoshida's comet list