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 (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.

  • Data science helps engineers discover new...
    on May 22, 2019 at 8:01 pm

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  • Unexpected observation of ice at low temperature,...
    on May 22, 2019 at 5:00 pm

    Through an experiment designed to create a super-cold state of water, scientists at the Department of Energy's Oak Ridge National Laboratory used neutron scattering to discover a pathway to the unexpected formation of dense, crystalline phases of ice thought to exist beyond Earth's limits. […]

  • Three exocomets discovered around the star Beta...
    on May 22, 2019 at 2:40 pm

    Just about a year after the launch of the NASA mission TESS, the first three comets orbiting the nearby star Beta Pictoris outside our solar system were discovered with data from the space telescope. The main goal of TESS is to search for exoplanets—planets orbiting other stars. The recognition of signals from much smaller exocomets compared to planets requires the analysis of a precise light curve, which can now be obtained using the technical sophistication of the new space telescope. […]

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    on May 21, 2019 at 8:18 am

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  • Wandering Earth: Rocket scientist explains how we...
    on May 16, 2019 at 2:30 pm

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  • COMET C/2019 J2 (Palomar)
    by Gareth V. Williams on May 13, 2019 at 12:34 am

    M.P.E.C. 2019-J123 Issued 2019 May 13, 00:16 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/2019 J1 (Lemmon)
    by Gareth V. Williams on May 12, 2019 at 11:33 pm

    M.P.E.C. 2019-J122 Issued 2019 May 12, 23:11 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/2019 H1 (NEOWISE)
    by Gareth V. Williams on May 4, 2019 at 4:51 pm

    M.P.E.C. 2019-J24 Issued 2019 May 4, 16:20 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 69P/Taylor
    by Gareth V. Williams on May 3, 2019 at 4:32 pm

    M.P.E.C. 2019-J22 Issued 2019 May 3, 16:29 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/2018 X2 (Fitzsimmons)
    by Gareth V. Williams on April 28, 2019 at 4:06 pm

    M.P.E.C. 2019-H76 Issued 2019 Apr. 28, 15:22 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 […]