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The nucleus of Comet Tempel 1.
The nucleus is the solid, central part of a comet, formerly termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and frozen gases. When heated by the Sun, the gases sublime and produce an atmosphere surrounding the nucleus known as the coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an albedo of 0.04.[1] This is blacker than coal, and may be caused by a covering of dust.[2]
Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[3][4] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[5][6] On 30 July 2015, scientists reported that the Philae spacecraft, that landed on comet 67P/Churyumov-Gerasimenko in November 2014, detected at least 16 organic compounds, of which four (including acetamide, acetone, methyl isocyanate and propionaldehyde) were detected for the first time on a comet.[7][8][9]
^Robert Roy Britt (29 November 2001). "Comet Borrelly Puzzle: Darkest Object in the Solar System". Space.com. Archived from the original on 22 January 2009. Retrieved 26 October 2008.
^"ESA Science & Technology: Halley". ESA. 10 March 2006. Retrieved 22 February 2009.
^Bauer, Markus (14 April 2015). "Rosetta and Philae Find Comet Not Magnetised". European Space Agency. Retrieved 14 April 2015.
^Schiermeier, Quirin (14 April 2015). "Rosetta's comet has no magnetic field". Nature. doi:10.1038/nature.2015.17327. S2CID 123964604.
^Agle, DC; Brown, Dwayne; Fohn, Joe; Bauer, Markus (2 June 2015). "NASA Instrument on Rosetta Makes Comet Atmosphere Discovery". NASA. Retrieved 2 June 2015.
^Feldman, Paul D.; A'Hearn, Michael F.; Bertaux, Jean-Loup; Feaga, Lori M.; Parker, Joel Wm.; et al. (2 June 2015). "Measurements of the near-nucleus coma of comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta" (PDF). Astronomy and Astrophysics. 583: A8. arXiv:1506.01203. Bibcode:2015A&A...583A...8F. doi:10.1051/0004-6361/201525925. S2CID 119104807.
^Jordans, Frank (30 July 2015). "Philae probe finds evidence that comets can be cosmic labs". The Washington Post. Associated Press. Archived from the original on 23 December 2018. Retrieved 30 July 2015.
^"Science on the Surface of a Comet". European Space Agency. 30 July 2015. Retrieved 30 July 2015.
^Bibring, J.-P.; Taylor, M.G.G.T.; Alexander, C.; Auster, U.; Biele, J.; Finzi, A. Ercoli; Goesmann, F.; Klingehoefer, G.; Kofman, W.; Mottola, S.; Seidenstiker, K.J.; Spohn, T.; Wright, I. (31 July 2015). "Philae's First Days on the Comet – Introduction to Special Issue". Science. 349 (6247): 493. Bibcode:2015Sci...349..493B. doi:10.1126/science.aac5116. PMID 26228139.
The nucleus is the solid, central part of a comet, formerly termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and...
radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers...
first trek into the inner Solar System. Its nucleus has an estimated average radius of 2.1 km (1.3 mi). The comet was discovered on 18 March 1973 by Czech...
(3.3 AU; 310 million mi) from the nucleus, showing that Hyakutake had the longest tail known for a comet. The comet was discovered on 30 January 1996...
hydrogen and methane in the cometnucleus have evaporated away, all that remains is an inert rock or rubble pile. A comet may go through a transition...
may also refer to: Active galactic nucleus in astronomy Cometnucleus, the solid, central part of a comet Cell nucleus, a central organelle of a eukaryotic...
for nearly one third of all comets. Most of these objects vaporize during their close approach, but a comet with a nucleus radius larger than 2–3 km is...
this to occur are: a large and active nucleus, a close approach to the Sun, and a close approach to the Earth. A comet fulfilling all three of these criteria...
a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying...
nucleus of Encke's Comet is 4.8 km. As its official designation implies, Encke's Comet was the first periodic comet discovered after Halley's Comet (designated...
larger than the Sun. The comet'snucleus was later estimated at 30–40 km in diameter. In many ways the comet was quite similar to Comet Hale–Bopp: it became...
Probe had captured an image of the comet, from which astronomers also estimated the diameter of the cometnucleus at approximately 5 km (3 mi). Later...
The CometNucleus Tour (CONTOUR) was a NASA Discovery-class space probe that failed shortly after its July 2002 launch. It was the only Discovery mission...
Comets (DIXI) mission used the Deep Impact spacecraft for a flyby mission to a second comet, Hartley 2. The goal was to take pictures of its nucleus to...
first time a comet had been photographed. Usherwood's photograph, which has not survived, showed the bright region around the comet'snucleus and a part...
lost. Comets can also run out of volatiles. Eventually most of the volatile material contained in a cometnucleus evaporates away, and the comet becomes...
announcement of opportunity was limited to six mission themes: Comet Surface Sample Return - a cometnucleus lander and sample return mission Lunar South Pole Sample...
CometNucleus Dust and Organics Return (CONDOR) is a mission concept to retrieve a sample from comet 67P/Churyumov–Gerasimenko to test ideas regarding...
CONSERT (COmetNucleus Sounding Experiment by Radiowave Transmission) is a scientific experiment on board the European Space Agency's Rosetta mission...
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