Comet

Cosma / Communication / Knowledge / Realm / Physical / Universe / Solar System / Small Body / Comet

—————————

Introduction1

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

OneLook, Free Dictionary, Wiktionary

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)
Encyclopædia Britannica

Portal

Solar System Exploration: Comets (NASA)

Search

Comets (Wolfram Alpha)

———————-

Innovation

Science

Solar System Exploration: Rosetta (NASA)
Rosetta (spacecraft)

————————–

Preservation

History

Comets throughout history (Windows to the Universe)

Quotation

Quotations Page

Library

WorldCat, Library of Congress, UPenn Online Books, Open Library

—————————

Participation

Education

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

Course

Crash Course Astronomy (YouTube)

OER Commons: Open Educational Resources

Community

Organization

International Astronomical Union (IAU)

News

, NPR Archives

News

Comet (Minor Planet Center, International Astronomical Union)
Science Daily, Phys.org, NPR Archives

Book

ISBNdb

Government

Comet Research (NASA)

Document

USA.gov

———————-

Expression

Fun

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

Poem

OEDILF: The Omnificent English Dictionary In Limerick Form

Music

Song Lyrics

returntotop


More News…

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.

  • Looking up at the asteroids in the neighborhood
    on January 19, 2022 at 2:08 pm

    Asteroids fly through our solar system all the time, but it's rare for us to take notice of them. But that's changed this week, as an asteroid passes within 1,231,184 miles of Earth on January 18. The asteroid, dubbed 7482 (1994 PC1), was first seen in 1994 and is about two-thirds of a mile wide.

  • Last nine years all among 10 hottest-ever, says US
    on January 15, 2022 at 4:00 pm

    The nine years spanning 2013-2021 all rank among the 10 hottest on record, according to an annual report a US agency released Thursday, the latest data underscoring the global climate crisis.

  • Atmospheric river storm observations over Pacific...
    on January 14, 2022 at 1:33 pm

    "Hurricane Hunter" aircraft are mobilizing for an expanded 13-week period that began Jan. 5 to glean critical data for improving forecasts of atmospheric river storms over the Pacific Ocean. Such storms provide up to half of the U.S. West Coast's annual precipitation and a majority of the flooding.

  • 'Don't Look Up': Real-world scientists comment on...
    on January 10, 2022 at 2:32 pm

    In the new Netflix movie "Don't Look Up," two actors playing fictional Michigan State University astronomers discover a comet on a collision course with Earth and struggle to convince people to take them seriously. The film is a satire about society's inability to cope with climate change.

  • 'Don't Look Up' shows bashing people over the...
    on January 7, 2022 at 3:13 pm

    The global top three programs on Netflix currently include the heroic quest of a monster hunter; the escapades of an American woman in Paris; and, at No. 1, a dark comedy about climate change called "Don't Look Up."


  • COMET P/2007 R1 = 2019 K3 (Larson)
    by Gareth V. Williams on June 3, 2019 at 9:59 pm

    M.P.E.C. 2019-L42 Issued 2019 June 3, 21:50 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/2000 S4 (LINEAR-Spacewatch)
    by Gareth V. Williams on June 2, 2019 at 1:45 pm

    M.P.E.C. 2019-L11 Issued 2019 June 2, 13:34 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 K1 (ATLAS)
    by Gareth V. Williams on May 25, 2019 at 2:26 pm

    M.P.E.C. 2019-K37 Issued 2019 May 25, 14:20 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 C/2019 JU6 (ATLAS)
    by Gareth V. Williams on May 24, 2019 at 2:52 pm

    M.P.E.C. 2019-K18 Issued 2019 May 24, 14:32 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 C/2019 J3 (ATLAS)
    by Gareth V. Williams on May 23, 2019 at 6:30 pm

    M.P.E.C. 2019-K14 Issued 2019 May 23, 18:24 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 […]

———————–

Adventures

Explore related posts on Cosma

  • 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!

——–
Related

Here are links to pages about closely related subjects.

Knowledge Realm

Physical

“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

——
Notes

1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.