Comet

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Posts

  • Octopuses from Space! (5/20/2018) - Did you hear the one about the octopuses from space? It sounds like the title of a cheesy sci-fi movie, doesn’t it? But it isn’t, this time, or at least, yet. Instead, it’s actually an oddball theory that’s been put forth in a recently published “scientific” article that’s getting quite a lot of buzz in … Continue reading Octopuses from Space!
  • RIP Rossetta! (10/1/2016) - The “Little Mission that Could” has come to an end, but what a mission it was to watch! Rosetta Concludes Mission with a Crash (Megan Gannon, Scientific American) Rosetta Mission Ends With Spacecraft’s Dive Into Comet (Kenneth Chang, New York Times) It was such a joy to watch each historic milestone the mission passed over … Continue reading RIP Rossetta!

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Solar System Exploration: Comets (NASA)

Dictionary

comet : a celestial body that appears as a fuzzy head usually surrounding a bright nucleus, that has a usually highly eccentric orbit, that consists primarily of ice and dust, and that often develops one or more long tails when near the sun — Webster

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Encyclopedia

Comet is a icy small Solar System body that, when passing close to the Sun, warms and begins to evolve gasses, 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.

As of November 2014 there are 5,253 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. 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. — Wikipedia

Comets (Eric Weisstein’s World of Astronomy, Wolfram Research)
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Comets throughout history (Windows to the Universe)

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Comets (Cosmos4Kids)
More to Explore: Asteroids, Comets and Meteorites (NASA)
Comets, Meteors & Asteroids (Ask an Astronomer, Cornell University)

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This Perfume Smells Like a Comet (Erin Blakemore, Smithsonian)

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Phys.org - latest science and technology news stories Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • The threat of centaur solar system objects for...
    on October 10, 2018 at 10:48 am

    Astrophysicists Mattia Galiazzo and Rudolf Dvorak from the University of Vienna, in collaboration with Elizabeth A. Silber (Brown University, U.S.) investigated the long-term path development of centaurs, solar system minor bodies that originally have orbits between Jupiter and Neptune. The researchers have estimated the number of close encounters and impacts with the terrestrial planets after the so-called Late Heavy Bombardment about 3.8 billion years ago, as well as the possible sizes of […]

  • SpaceX satellite launch lights up night sky,...
    on October 8, 2018 at 5:42 pm

    When SpaceX launched a rocket carrying an Argentine Earth-observation satellite from California's Central Coast, both the night sky and social media lit up. […]

  • Vesta reveals the childhood of the Solar System
    on October 8, 2018 at 11:59 am

    Investigating the earliest and least-known phases of the history of the solar system, when the young sun was still enveloped by a disk of gas and dust in which the planets began to form, is probably one of the most complex challenges in modern planetary science. The existing celestial bodies that formed at the time are few, and in the majority of cases, evidence of the ancient processes that marked the birth of the solar system has been lost. […]

  • Astrophysicists study the 'profile' of coma in...
    on October 2, 2018 at 2:17 pm

    Far Eastern Federal University (FEFU) scientists, together with astrophysicists from all over the world, are observing as the Comet 21P/Giacobini-Zinner approaches the Earth. The favorable weather conditions in September in Primorsky Krai, Russia, made it possible to receive the quality images of the object. The scientists are currently preparing an article for publication. […]

  • Image: Comet landscape
    on October 1, 2018 at 2:30 pm

    On 30 September 2016, ESA's Rosetta spacecraft came closer than ever to the target it had studied from afar for more than two years, concluding its mission with a controlled impact onto the surface of Comet 67P/Churyumov-Gerasimenko (67P/C-G). […]


  • COMET C/2017 M4 (ATLAS)
    by Gareth V. Williams on June 23, 2017 at 3:34 pm

    M.P.E.C. 2017-M45 Issued 2017 June 23, 15:30 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network […]

  • COMET C/2017 M3 (PANSTARRS)
    by Gareth V. Williams on June 23, 2017 at 3:23 pm

    M.P.E.C. 2017-M44 Issued 2017 June 23, 15:20 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network […]

  • COMET P/2004 T1 = 2017 M2 (LINEAR-NEAT)
    by Gareth V. Williams on June 22, 2017 at 10:39 am

    M.P.E.C. 2017-M40 Issued 2017 June 22, 10:35 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network […]

  • COMET P/2010 A2 (LINEAR)
    by Gareth V. Williams on June 21, 2017 at 10:46 am

    M.P.E.C. 2017-M38 Issued 2017 June 21, 10:43 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network […]

  • COMET P/2009 S2 = 2017 M1 (McNaught)
    by Gareth V. Williams on June 20, 2017 at 11:54 am

    M.P.E.C. 2017-M28 Issued 2017 June 20, 11:51 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network […]