(7) Iris
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Asteroid (7) Iris 
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| Recorded by VLT-SPHERE | |
| Properties of the orbit ( animation ) | |
| Orbit type | Main belt asteroid |
| Major semi-axis | 2.386 AU |
| eccentricity | 0.231 |
| Perihelion - aphelion | 1.836 AU - 2.936 AU |
| Inclination of the orbit plane | 5.5 ° |
| Length of the ascending node | 259.7 ° |
| Argument of the periapsis | 145.2 ° |
| Time of passage of the perihelion | 18th November 2017 |
| Sidereal period of rotation | 3 a 251 d |
| Mean orbital velocity | 19.01 km / s |
| Physical Properties | |
| Medium diameter | 199.83 (± 10) km |
| Dimensions | 1.25 x 10 19 kg |
| Albedo | 0.28 |
| Medium density | ≈ 1.8 g / cm³ |
| Rotation period | 7.1 h |
| Absolute brightness | 5.5 mag |
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Spectral class (according to Tholen) |
S. |
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Spectral class (according to SMASSII) |
S. |
| history | |
| Explorer | John R. Hind |
| Date of discovery | August 13, 1847 |
| 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. | |
(7) Iris is an asteroid of the main belt , which on 13 August 1847 by John Russell Hind was discovered as the seventh asteroid.
The heavenly body was named after Iris , a messenger of the gods from Greek mythology .
Iris moves at a distance of 1.8 ( perihelion ) to 2.9 ( aphelion ) astronomical units , in 3.7 years on an eccentric orbit around the sun . The orbit is inclined 5.5 ° to the ecliptic , the orbital eccentricity is 0.23.
With a mean diameter of around 200 km, Iris is one of the largest asteroids in the main belt. Your rotation period is 7.1 hours.
Iris has a relatively light, silicate-rich surface with an albedo of 0.28. During opposition , Iris reaches a brightness of 8.1 mag , making it one of the brightest asteroids in the night sky. To find them, however, you need a telescope or bright prism binoculars .
See also
Web links
Individual evidence
- ↑ Elena V. Pitjeva: High-Precision Ephemerides of Planets — EPM and Determination of Some Astronomical Constants . In: Solar System Research . tape 39 , no. 3 , p. 176-186 , doi : 10.1007 / s11208-005-0033-2 .