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.

  • Do volcanoes or an asteroid deserve blame for...
    on February 21, 2019 at 7:00 pm

    UC Berkeley scientists have obtained more precise dates for the Deccan Traps volcanic lava flows, linking peak activity more closely to the asteroid or comet impact 66 million years ago and the coincident mass extinction. But if greenhouse gases emitted before the impact created a hothouse climate that set life up for a fall when the impact cooled the planet, those gases did not coincide with the largest lava flows from the Deccan Traps. […]

  • Applying computational chemistry to simulate...
    on February 21, 2019 at 2:50 pm

    The waters of science are muddy these days—especially at the University of California San Diego where all that separates a chemist from a physicist in some cases is office drywall. Chemists ask the questions in their experiments, and physicists supply the answers with the tools needed to do the job. Sometimes that job needs to be quicker and easier, so a computational expert is called in. Add a biological specialist to the mix and you've got a recipe for cutting-edge science that breaks […]

  • Neptune's newest, tiniest moon likely piece of...
    on February 20, 2019 at 8:10 pm

    Neptune's newest and tiniest moon is probably an ancient piece of a much larger moon orbiting unusually close. […]

  • Ingredients for water could be made on surface of...
    on February 20, 2019 at 5:17 pm

    When a stream of charged particles known as the solar wind careens onto the Moon's surface at 450 kilometers per second (or nearly 1 million miles per hour), they enrich the Moon's surface in ingredients that could make water, NASA scientists have found. […]

  • Close encounters: planning for extra Hera flyby
    on February 20, 2019 at 4:04 pm

    ESA's proposed Hera mission will already visit two asteroids: the Didymos binary pair. The Hera team hopes to boost that number by performing a flyby of another asteroid during the mission's three-year flight. […]


  • COMET C/2018 Y1 (Iwamoto)
    by Gareth V. Williams on February 16, 2019 at 1:50 am

    M.P.E.C. 2019-D01 Issued 2019 Feb. 16, 01:47 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 A9 (PANSTARRS)
    by Gareth V. Williams on February 7, 2019 at 4:16 pm

    M.P.E.C. 2019-C53 Issued 2019 Feb. 7, 16:08 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/2019 B2 (Groeller)
    by Gareth V. Williams on February 4, 2019 at 4:22 am

    M.P.E.C. 2019-C21 Issued 2019 Feb. 4, 04:02 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/2019 A8 (PANSTARRS)
    by Gareth V. Williams on February 4, 2019 at 3:45 am

    M.P.E.C. 2019-C20 Issued 2019 Feb. 4, 03:32 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/2018 V5 (Trujillo-Sheppard)
    by Gareth V. Williams on February 3, 2019 at 9:20 pm

    M.P.E.C. 2019-C18 Issued 2019 Feb. 3, 20:41 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 […]