(24) Themis
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Asteroid (24) Themis |
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|---|---|
| Properties of the orbit ( animation ) | |
| Orbit type | Outer main belt |
| Asteroid family | Themis family |
| Major semi-axis | 3.135 AU |
| eccentricity | 0.126 |
| Perihelion - aphelion | 2.741 AU - 3.529 AU |
| Inclination of the orbit plane | 0.8 ° |
| Length of the ascending node | 35.9 ° |
| Argument of the periapsis | 106.7 ° |
| Time of passage of the perihelion | May 24, 2019 |
| Sidereal period of rotation | 5 a 201 d |
| Mean orbital velocity | 16.8 km / s |
| Physical Properties | |
| Medium diameter | 198 km |
| Albedo | 0.067 |
| Rotation period | 8 h 22 min |
| Absolute brightness | 7.1 likes |
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Spectral class (according to Tholen) |
C. |
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Spectral class (according to SMASSII) |
B. |
| history | |
| Explorer | Annibale De Gasparis |
| Date of discovery | April 5, 1853 |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items. | |
(24) Themis is an asteroid of the main asteroid belt discovered by Annibale De Gasparis on April 5, 1853 . The name is derived from Themis , the daughter of Uranus and Gaia in Greek mythology .
properties
With a diameter of around 200 kilometers, Themis is one of the largest asteroids in the main belt. It has a dark surface with an albedo of 0.067. Themis rotates around its own axis in 8 hours and 22 minutes.
In 2008, a Hawaiian telescope ( Infrared Telescope Facility ) discovered water ice on the surface of the asteroid. In the journal Nature, two research teams report on the surprising discovery of ice on the surface. According to this, the asteroid is wrapped in a thin layer of frozen water. A detailed study based on the absorption behavior in the near-infrared reflection spectrum confirms this observation and at the same time provides indications of organic compounds on the surface of the asteroid.
Themis was also the name of a 10th Saturn moon supposedly discovered by William Henry Pickering in 1905 , but the discovery of which could never be confirmed.
See also
literature
- AS Rivkin, JP Emery: Water Ice On 24 Themis ?. Asteroids, Comets, Meteors (2008) lpi.usra.edu (PDF)
Web links
- Ice confirmed on an asteroid . In: American Scientist , October 7, 2009
- Asteroid isn't just a dry heap of rubble . In: New Scientist October 12, 2009
Individual evidence
- ^ Confirming Water Ice on the Surface of Asteroid 24 Themis . American Astronomical Society, 2009, bibcode : 2009DPS .... 41.3205C
- ↑ Asteroid Themis has a crust of ice .
- ^ Humberto Campins et al .: Water ice and organics on the surface of the asteroid 24 Themis . In: Nature , 2010, Volume 464, pp. 1320-1321