21 Lutetia
Encyclopedia : 2 : 21 : 21L : 21 Lutetia
| Orbital elements | |
|---|---|
| Eccentricity (orbit)>e | |
| Inclination>i | ° |
| Perihelion>q | AU |
| Argument of perihelion>ω | ° |
| Semi-major axis>a | AU |
| Longitude of the ascending node>ω | ° |
| Aphelion>Q | AU |
| Mean anomaly>M | ° |
| Orbital period>P | years |
| Mean motion>n | °/day |
| Time of perihelion passage>TP | |
21 Lutetia (lew-tee'-shə ([[Help:Pronunciation respelling key|key]])) is a large Main belt asteroid of the M spectral type, about 100 kilometers in diameter.
Characteristics
The composition of Lutetia has puzzled astronomers for some time, and its investigation has picked up in recent years in anticipation of the upcoming Rosetta flyby. While classified as the M spectral type, it is one of the anomalous members which do not display much evidence of metal on their surface. In fact, there are various indications of a non-metallic surface: A flat low frequency spectrum that behaves like carbonaceous chondrites and C-type asteroids and not at all like metallic meteorites, A low radar albedo whereas strongly metallic asteroids like e.g. 16 Psyche have a high one , evidence of hydrated materials on its surface , abundant silicates and a thicker regolith than most asteroids .Lightcurve analysis indicates that Lutetia's pole points towards either ecliptic coordinates (β, λ) = (3°, 40°) or (β, λ) = (3°, 220°) with a 10° uncertainty . This gives an axial tilt of 85°, or 89°, respectively, meaning that Lutetia spins at an approximately right angle to the ecliptic like e.g. Uranus.
Exploration
Lutetia was discovered on November 15, 1852 by Hermann Mayer Salomon Goldschmidt at the observatory of Paris. The name Lutetia derives from the Latin name for Paris.On July 10, 2010 the European Rosetta comet probe will pass the asteroid with a minimum distance of 3000 km on its way to 67P/Churyumov-Gerasimenko. In the run-up to this event the attention of astronomers has been drawn to Lutetia.
The flyby will be rather important for the understanding of the asteroids, since Lutetia is not only large but also the first M-type asteroid to be visited by a spacecraft. The flyby probe will provide much new information on the composition of the M-type asteroids, which is varied, uncertain and under much debate. Lutetia is one of the anomalous members of the type whose metallic content is in doubt.
There have been two reported stellar occultations by Lutetia: from Malta (1997) and Australia (2003), with only one chord each, roughly agreeing with IRAS measurments.
External links
References
Aspects
| Conjunction to Sun | Stationary, than retrograde | Opposition | Minimal distance to Earth (AU) | Maximum brightness (mag) | stationary, than prograde |
|---|---|---|---|---|---|
| 28. December 2005 | 15. February 2006 | 1,84371 | 11,1 | 09. April 2006 | 03. July 2005 |
| 16. April 2007 | 30.May 2007 | 1,30257 | 9,9 | 17. July 2007 | 05. October 2006 |
| 12. October 2008 | 29. November 2008 | 1,42348 | 10,1 | 14. January 2009 | 01. March 2008 |
| 14. January 2010 | 04. March 2010 | 1,82843 | 11,1 | 27. April 2010 | 23. July 2009 |
| 23.May 2011 | 03. July 2011 | 1,13050 | 9,4 | 14. August 2011 | 25. October 2010 |
| 02. November 2012 | 22. December 2012 | 1,58913 | 10,5 | 07. February 2013 | 09. April 2012 |
| 01. February 2014 | 21. March 2014 | 1,76440 | 11,0 | 14.May 2014 | 10. August 2013 |
| 06. July 2015 | 13. August 2015 | 1,03631 | 9,3 | 22. September 2015 | 17. November 2014 |
| 21. November 2016 | 10. January 2017 | 1,71894 | 10,8 | 01. March 2017 | 12.May 2016 |
| 20. February 2018 | 09. April 2018 | 1,65344 | 10,8 | 02. June 2018 | 28. August 2017 |
| 16. August 2019 | 24. September 2019 | 1,07768 | 9,4 | 05. November 2019 | 15. December 2018 |
| 09. December 2020 | 28. January 2021 | 1,80461 | 11,0 | 20. March 2021 | 08. June 2020 |
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