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Asteroid



The first few asteroids discovered were assigned symbols like the ones traditionally used to designate Earth, the Moon, the Sun and planets. The symbols quickly became ungainly, hard to draw and recognise. By the end of 1851 there were 15 known asteroids, each (except one) with its own symbol(s).[30]

Asteroid Symbol
Ceres Old planetary symbol of Ceres Variant symbol of Ceres Sickle variant symbol of Ceres Other sickle variant symbol of Ceres
2 Pallas Old symbol of Pallas Variant symbol of Pallas
3 Juno Old symbol of Juno Other symbol of Juno
4 Vesta Old symbol of Vesta Old planetary symbol of Vesta Modern astrological symbol of Vesta
5 Astraea
6 Hebe
7 Iris
8 Flora
9 Metis
10 Hygiea
11 Parthenope
12 Victoria
13 Egeria Never assigned.
14 Irene "A dove carrying an olive-branch, with a star on its head," never drawn.[31]
15 Eunomia
28 Bellona
35 Leukothea
37 Fides

Johann Franz Encke made a major change in the Berliner Astronomisches Jahrbuch (BAJ, Berlin Astronomical Yearbook) for 1854. He introduced encircled numbers instead of symbols, although his numbering began with Astraea, the first four asteroids continuing to be denoted by their traditional symbols. This symbolic innovation was adopted very quickly by the astronomical community. The following year (1855), Astraea's number was bumped up to 5, but Ceres through Vesta would be listed by their numbers only in the 1867 edition. A few more asteroids (28 Bellona,[32] 35 Leukothea,[33] and 37 Fides[34]) would be given symbols as well as using the numbering scheme. The circle would become a pair of parentheses, and the parentheses sometimes omitted altogether over the next few decades.[31]

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Exploration

Until the age of space travel, objects in the asteroid belt were merely pinpricks of light in even the largest telescopes and their shapes and terrain remained a mystery. The best modern ground-based telescopes, as well as the Earth-orbiting Hubble Space Telescope, can resolve a small amount of detail on the surfaces of the very largest asteroids, but even these mostly remain little more than fuzzy blobs. Limited information about the shapes and compositions of asteroids can be inferred from their light curves (their variation in brightness as they rotate) and their spectral properties, and asteroid sizes can be estimated by timing the lengths of star occulations (when an asteroid passes directly in front of a star). Radar imaging can yield good information about asteroid shapes and orbital and rotational parameters, especially for near-Earth asteroids.

The first close-up photographs of asteroid-like objects were taken in 1971 when the Mariner 9 probe imaged Phobos and Deimos, the two small moons of Mars, which are probably captured asteroids. These images revealed the irregular, potato-like shapes of most asteroids, as did subsequent images from the Voyager probes of the small moons of the gas giants.

951 Gaspra, the first asteroid to be imaged in close up.
951 Gaspra, the first asteroid to be imaged in close up.

The first true asteroid to be photographed in close-up was 951 Gaspra in 1991, followed in 1993 by 243 Ida and its moon Dactyl, all of which were imaged by the Galileo probe en route to Jupiter.

The first dedicated asteroid probe was NEAR Shoemaker, which photographed 253 Mathilde in 1997, before entering into orbit around 433 Eros, finally landing on its surface in 2001.

Other asteroids briefly visited by spacecraft en route to other destinations include 9969 Braille (by Deep Space 1 in 1999), and 5535 Annefrank (by Stardust in 2002).

In September 2005, the Japanese Hayabusa probe started studying 25143 Itokawa in detail and may return samples of its surface to earth. The Hayabusa mission has been plagued with difficulties, including the failure of two of its three control wheels, rendering it difficult to maintain its orientation to the sun to collect solar energy. Following that, the next asteroid encounters will involve the European Rosetta probe (launched in 2004), which will study 2867 Šteins and 21 Lutetia in 2008 and 2010.

In September 2007, NASA launched the Dawn Mission, which will orbit the dwarf planet Ceres and the asteroid 4 Vesta in 2011-2015, with its mission possibly then extended to 2 Pallas.

It has been suggested that asteroids might be used in the future as a source of materials which may be rare or exhausted on earth (asteroid mining), or materials for constructing space habitats (see Colonization of the asteroids). Materials that are heavy and expensive to launch from earth may someday be mined from asteroids and used for space manufacturing and construction.

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In fiction

Main article: Asteroids in fiction

Asteroids and asteroid belts are a staple of science fiction stories. Asteroids play several potential roles in science fiction: as places which human beings might colonize; as resources for extracting minerals; as a hazard encountered by spaceships travelling between two other points; and as a threat to life on Earth due to potential impacts.

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See also

Look up asteroid in
Wiktionary, the free dictionary.

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References

  1. ^ Beech, M.; Steel, D. I. (September 1995). "On the Definition of the Term Meteoroid". Quarterly Journal of the Royal Astronomical Society 36 (3): 281–284. 
  2. ^ Ceres, originally considered a new planet, was the largest asteroid known but is now classified as a dwarf planet. All other asteroids are now classified as small solar system bodies.
  3. ^ World Book at NASA
  4. ^ English Dictionary - Browsing Page P-44. HyperDictionary.com. Retrieved on 2008-04-15.
  5. ^ "Are Kuiper Belt Objects asteroids?", "Ask an astronomer", Cornell University
  6. ^ "Asteroids and Comets", NASA website
  7. ^ "Comet Dust Seems More Asteroidy" Scientific American, January 25, 2008
  8. ^ "Comet samples are surprisingly asteroid-like", New Scientist, 24 January 2008
  9. ^ Questions and Answers on Planets, IAU
  10. ^ "Three new planets may join solar system", New Scientist, 16 August 2006
  11. ^ JPL. How Many Solar System Bodies. JPL Solar System Dynamics. NASA. Retrieved on 2008-05-21.
  12. ^ Minor Planet Statistics. Minor Planet Center. Retrieved on 2008-03-22.
  13. ^ Minor Planet Names. Minor Planet Center. Retrieved on 2008-05-21.
  14. ^ Discovery Circumstances: Numbered Minor Planets (1)-(5000). Minor Planet Center. Retrieved on 2006-10-11.
  15. ^ Discovery Circumstances: Numbered Minor Planets (175001)-(180000). Minor Planet Center. Retrieved on 2008-05-21.
  16. ^ European Space Agency (April 4, 2002). "New study reveals twice as many asteroids as previously believed". Press release. Retrieved on 2008-02-21.
  17. ^ Krasinsky, G. A.; Pitjeva, E. V.; Vasilyev, M. V.; Yagudina, E. I. (July 2002). "Hidden Mass in the Asteroid Belt". Icarus 158 (1): 98–105. doi:10.1006/icar.2002.6837. 
  18. ^ Pitjeva, E. V. (2004). "Estimations of masses of the largest asteroids and the main asteroid belt from ranging to planets, Mars orbiters and landers". 35th COSPAR Scientific Assembly. Held 18-25 July 2004, in Paris, France: 2014. 
  19. ^ Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschle, C. (1995). "Asteroid families: Search of a 12,487-asteroid sample using two different clustering techniques". Icarus 116: 291–314. doi:10.1006/icar.1995.1127. 
  20. ^ Chapman, C. R.; Morrison, D.; Zellner, B. (1975). "Surface properties of asteroids: A synthesis of polarimetry, radiometry, and spectrophotometry". Icarus 25: 104–130. doi:10.1016/0019-1035(75)90191-8. 
  21. ^ Tholen, D. J. (March 8-11, 1988). "Asteroid taxonomic classifications". Asteroids II; Proceedings of the Conference: pp. 1139-1150, Tucson, AZ: University of Arizona Press. Retrieved on 2008-04-14. 
  22. ^ Bus, S. J.; Binzel, R. P. (2002). "Phase II of the Small Main-belt Asteroid Spectroscopy Survey: A feature-based taxonomy". Icarus 158: 146. doi:10.1006/icar.2002.6856. 
  23. ^ McSween Jr., Harry Y. (1999). Meteorites and their Parent Planets, 2nd edition, Oxford University Press. ISBN 0521587514. 
  24. ^ Chapman, Mary G. (May 17, 1992). Carolyn Shoemaker, Planetary Astronomer and Most Successful 'Comet Hunter' To Date. USGS. Retrieved on 2008-04-15.
  25. ^ Yeomans, Don. Near Earth Object Search Programs. NASA. Retrieved on 2008-04-15.
  26. ^ Minor Planet Discover Sites. Retrieved on 2007-08-31.
  27. ^ Unusual Minor Planets. Retrieved on 2007-08-31.
  28. ^ Citation from MPC 55988. Retrieved on 2006-06-05.
  29. ^ Staff. "Lucy Crespo da Silva, 22, a senior, dies in fall", Hubble News Desk, November 28, 2000. Retrieved on 2008-04-15. 
  30. ^ Gould, B. A. (1852). "On the Symbolic Notation of the Asteroids". Astronomical Journal 2: 80. doi:10.1086/100212. 
  31. ^ a b Hilton, James L. (September 17, 2001). When Did the Asteroids Become Minor Planets. Retrieved on 2006-03-26.
  32. ^ Encke, J. F. (1854). "Beobachtung der Bellona, nebst Nachrichten über die Bilker Sternwarte". Astronomische Nachrichten 38: 143. doi:10.1002/asna.18540380907. 
  33. ^ Rümker, G.; Peters, C. A. F. (1855). "Name und Zeichen des von Herrn R. Luther zu Bilk am 19. April entdeckten Planeten". Astronomische Nachrichten 40: 373. doi:10.1002/asna.18550402405. 
  34. ^ Luther, R. (1856). "Schreiben des Herrn Dr. R. Luther, Directors der Sternwarte zu Bilk, an den Herausgeber". Astronomische Nachrichten 42: 107. doi:10.1002/asna.18550420705. 

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External links

Wikimedia Commons has media related to:
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The Solar System
The Sun Mercury Venus The Moon Earth Phobos and Deimos Mars Ceres The asteroid belt Jupiter Moons of Jupiter Saturn Moons of Saturn Uranus Moons of Uranus Moons of Neptune Neptune Moons of Pluto Pluto The Kuiper Belt Dysnomia Eris The Scattered Disc The Oort Cloud
See also astronomical objects, the Solar System's list of objects, sorted by radius or mass, and the Solar System Portal
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Minor planets navigator

1 Ceres       ·       2 Pallas
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Small Solar System bodies
Lists: Minor planets · Asteroid groups and families · Binary asteroids · Asteroid moons
See also: Near-Earth object · Dwarf planet · Planet · Solar System · Pronunciation of asteroid names · Meanings of asteroid names.




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