311P/PANSTARRS also known as P/2013 P5 (PANSTARRS) is an asteroid (or main-belt comet) discovered by the Pan-STARRS telescope on 27 August 2013.[4] Observations made by the Hubble Space Telescope revealed that it had six comet-like tails.[5] The tails are suspected to be streams of material ejected by the asteroid as a result of a rubble pile asteroid spinning fast enough to remove material from it.[2] This is similar to 331P/Gibbs, which was found to be a quickly-spinning rubble pile as well.

Three-dimensional models constructed by Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany, showed that the tails could have formed by a series of periodic impulsive dust-ejection events,[6] radiation pressure from the sun then stretched the dust into streams.[5]

Precovery images from the Sloan Digital Sky Survey from 2005 were found, showing negligible cometary activity in 2005.

Asteroid P2013 P5 v2
P/2013 P5 (PANSTARRS) as captured by the Hubble Space Telescope
Discovered byPan-STARRS
Discovery date27 August 2013
Main-belt comet
Orbital characteristics[1]
Epoch 2013-Nov-16.0
Uncertainty parameter 0
Observation arc13.13 yr (4,797 d)
Aphelion2.4411 AU
Perihelion1.9362 AU
2.1885 AU
3.24 yr (1182.575d)
Physical characteristics
Mean diameter
~480 meters (1,570 ft) [2]
Mean density
3300±200 kg m3 [3]
~0.240 meters (9.4 in) per second


The asteroid has a radius of about 240 meters (790 ft).[2] The first images taken by Pan-STARRS revealed that the object had an unusual appearance: asteroids generally appear as small points of light, but P/2013 P5 was identified as a fuzzy-looking object by astronomers.[7] The multiple tails were observed by the Hubble Space Telescope on 10 September 2013, Hubble later returned to the asteroid on 23 September, its appearance had totally changed. It looked as if the entire structure had swung around.[8] The Hubble Space Telescope continued to track the object through 11 February 2014.[9] The comet-like appearance has resulted in the asteroid being named as a comet. The object has a low orbital inclination and always stays outside the orbit of Mars.[1]

See also


  1. ^ a b "JPL Small-Body Database Browser: P/2013 P5 (PANSTARRS)" (2013-11-07 last obs). Retrieved 2013-11-09.
  2. ^ a b c Jewitt, D.; Agarwal, J.; Weaver, H.; Mutchler, M.; Larson, S. (2013). "The Extraordinary Multi-Tailed Main-Belt Comet P/2013 P5". The Astronomical Journal. 778: L21. arXiv:1311.1483. Bibcode:2013ApJ...778L..21J. doi:10.1088/2041-8205/778/1/L21.
  3. ^ "The Extraordinary Multi-Tailed Main-Belt Comet P/2013 P5" (PDF). Spacetelescope.
  4. ^ "When is a comet not a comet?". Spacetelescope. 7 November 2013.
  5. ^ a b "NASA's Hubble Sees Asteroid Spouting Six Comet-Like Tails". Hubblesite. 7 November 2013.
  6. ^ "She calculated that dust-ejection events occurred on April 15, July 18, July 24, Aug. 8, Aug. 26 and Sept. 4"
  7. ^ "When is a comet not a comet?". ESA. 7 November 2013.
  8. ^ "Hubble astronomers observe bizarre six-tailed asteroid". Spacetelescope. 7 November 2013.
  9. ^ "311P/PANSTARRS Orbit". Minor Planet Center. Retrieved 2014-09-13.

External links


276P/Vorobjov (previously P/2012 T7 (VOROBJOV)) is a Jupiter-family comet discovered on 15 October 2012 by Tomáš Vorobjov on three 120-s images taken remotely using the 0.81-m f/7 Ritchey-Chretien Schulman Telescope located at the Mt. Lemmon SkyCenter via the Sierra Stars Observatory Network in the course of a minor-planet search survey undertaken as part of the International Astronomical Search Collaboration (IASC) school campaigns. After posting on the Minor Planet Center's NEOCP webpage, other observers have commented on the object's cometary appearance. The discovery was announced by the Minor Planet Center on 18 October, three days after the discovery.


331P/Gibbs (P/2012 F5) is a small periodic Encke-type and rare main-belt comet, discovered by American amateur astronomer Alex Gibbs.


354P/LINEAR (formerly P/2010 A2 (LINEAR)) is a small Solar System body that displayed characteristics of both an asteroid and a comet, and thus, was initially given a cometary designation. Because it has the orbit of a main-belt asteroid and showed the tail of a comet, it was listed as a main-belt comet. But within a month of discovery, an analysis of images by the Hubble telescope suggested that its tail was generated by dust and gravel resulting from a recent head-on collision between asteroids rather than from sublimation of cometary ice. This was the first time a small-body collision had been observed; since then, minor planet 596 Scheila has also been seen to undergo a collision, in late 2010. The position of the nucleus was remarkable for being offset from the axis of the tail and outside the dust halo, a situation never before seen in a comet. The tail is created by millimeter-sized particles being pushed back by solar radiation pressure.

C/2012 E2 (SWAN)

Comet C/2012 E2 (SWAN) was a Kreutz group sungrazing comet discovered by Vladimir Bezugly in publicly available images taken by the SWAN instrument (Solar Wind ANisotropies) on board the SOHO spacecraft. It is recognized for being the first Kreutz sungrazer observed in SWAN imagery.

C/2015 F3

Comet C/2015 F3 (SWAN) was discovered in March 2015 by Rob Matson, Vladimir Bezugly and Michael Matiazzo in near real time images taken by the SWAN instrument aboard the SOHO spacecraft. At discovery the comet was already shining at around 10th magnitude as it was already near perihelion

. Orbital studies revealed C/2015 F3 to be a related fragment to long periodic comets C/1988 A1 (Liller) and C/1996 Q1 (Tabur), which were already thought to have broken off each other at a previous perihelion passage. As of May 2015, Comet SWAN was fading rapidly, as both C/1988 A1 and C/1996 Q1 ultimately did. .

C/2015 F5 (SWAN-XingMing)

Comet C/2015 F5 (SWAN-XingMing) was discovered on March 29, 2015 in near real time SWAN images of the SOHO spacecraft, by Szymon Liwo and Worachate Boonplod. It was also independently discovered on April 4, 2015 by Guoyou Sun and Gao Xing at the XingMing observatory near Ürümqi, China. At discovery, the comet had just passed perihelion and was only 0,35 AU from the Sun, shining at about +10 mag. As of May 2015 the comet had faded below mag +13. The comet is periodic with an orbital period of about 61 years .


A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earth's diameter, while the tail may stretch one astronomical unit. If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star. Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition.

Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma (the central part immediately surrounding the nucleus) and the tail (a typically linear section consisting of dust or gas blown out from the coma by the Sun's light pressure or outstreaming solar wind plasma). However, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System. The discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called Manx comets. They are still classified as comets, such as C/2014 S3 (PANSTARRS). 27 Manx comets were found from 2013 to 2017.As of July 2018 there are 6,339 known comets, a number that is steadily increasing as they are discovered. However, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System (in the Oort cloud) is estimated to be one trillion. Roughly one comet per year is visible to the naked eye, though many of those are faint and unspectacular. Particularly bright examples are called "great comets". Comets have been visited by unmanned probes such as the European Space Agency's Rosetta, which became the first ever to land a robotic spacecraft on a comet, and NASA's Deep Impact, which blasted a crater on Comet Tempel 1 to study its interior.

Comet Encke

Comet Encke or Encke's Comet (official designation: 2P/Encke) is a periodic comet that completes an orbit of the Sun once every 3.3 years. (This is the shortest period of a reasonably bright comet; the faint main-belt comet 311P/PANSTARRS has a period of 3.2 years.) Encke was first recorded by Pierre Méchain in 1786, but it was not recognized as a periodic comet until 1819 when its orbit was computed by Johann Franz Encke; like Halley's Comet, it is unusual in being named after the calculator of its orbit rather than its discoverer. Like most comets, it has a very low albedo, reflecting only 4.6% of the light it receives. The diameter of the nucleus of Encke's Comet is 4.8 km.

List of Pan-STARRS discoveries

PANSTARRS or variation may refer to:

Pan-STARRS, the Panoramic Survey Telescope and Rapid Response System in Hawaii, United States


C/2011 L4 Pan-Starrs



P/2013 P5 (PANSTARRS), Main-Belt Comet









Interstellar Object

1I/2017 U1 (ʻOumuamua), Interstellar Asteroid discovered by Pan-STARRS

List of numbered comets

This is a list of periodic comets that were numbered by the Minor Planet Center after having been observed on at least two occasions. As of October 2018 there are 375 numbered comets (1P–375P), most of them being members of the Jupiter-family (JFC). There are also 27 Encke-type comets (ETCs), 14 Halley-type comets (HTCs), 4 Chiron-type comets (CTCs), and one long-period comet (i.e. 153P). Many of these bodies are also near-Earth comets (NECs). In addition, 8 numbered comets are principally classified as minor planets – five main-belt comets, two centaurs (CEN), and one Apollo asteroid – and display characteristics of both an asteroid and a comet.

Occasionally, comets will break up into multiple chunks, as volatiles coming off the comet may cause it to break into two or more pieces. An extreme example of this is 73P/Schwassmann–Wachmann, which broke into over 50 pieces during its 1995 perihelion.

For a larger list of periodic Jupiter-family and Halley-type comets including unnumbered bodies, see list of periodic comets.

Main-belt comet

Main-belt comets (MBCs) are bodies orbiting within the asteroid belt that have shown comet-like activity during part of their orbit. The Jet Propulsion Laboratory defines a main-belt asteroid as an asteroid with a semi-major axis (average distance from the Sun) of more than 2 AU but less than 3.2 AU, and a perihelion (closest approach distance to the Sun) of no less than 1.6 AU. David Jewitt from UCLA points out that these objects are most likely not comets with sublimating ice, but asteroids that exhibit dust activity, and hence he and others started calling these class of objects active asteroids.

The first main-belt comet discovered is 7968 Elst–Pizarro. It was discovered in 1979 and was found to have a tail by Eric Elst and Guido Pizarro in 1996 and given the cometary designation 133P/Elst-Pizarro.

2013 in space
Impact events

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