7 Iris
|
|
| Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html) | |
|---|---|
| Discoverer | John Russell Hind |
| Discovery date | August 13, 1847 |
| Alternate designations | B (http://cfa-www.harvard.edu/iau/MPDes.html) |
| Category | Main belt |
| Orbital elements C (http://asteroid.lowell.edu/) Epoch July 14, 2004 (JD 2453200.5) | |
| Eccentricity (e) | 0.230 |
| Semi-major axis (a) | 357.019 Gm (2.387 AU) |
| Perihelion (q) | 274.729 Gm (1.836 AU) |
| Aphelion (Q) | 439.310 Gm (2.937 AU) |
| Orbital period (P) | 1346.628 d (3.69 a) |
| Mean orbital speed | 19.28 km/s |
| Inclination (i) | 5.523° |
| Longitude of the ascending node (Ω) | 259.766° |
| Argument of perihelion (ω) | 145.406° |
| Mean anomaly (M) | 135.770° |
| Physical characteristics | |
| Dimensions | 199.8 km |
| Mass | 8.4×1018 kg |
| Density | 2 ? g/cm³ |
| Surface gravity | 0.0558 m/s² |
| Escape velocity | 0.1056 km/s |
| Rotation period | 0.2975 d 1 (http://www.psi.edu/pds/archive/lc.html) |
| Spectral class | S-type asteroid |
| Absolute magnitude | 5.51 |
| Albedo | 0.277 2 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html) |
| Mean surface temperature | ~174 K |
7 Iris (eye'-ris) is one of the largest Main belt asteroids. The Iridian surface is very bright-colored and is probably a mixture nickel-iron metals and magnesium- and iron-silicates.
It was the seventh asteroid discovered, on August 13, 1847 by J. R. Hind from London, UK. It was his first asteroid discovery.
It was named after the rainbow goddess Iris of Greek mythology, sister of the Harpies and messenger of the gods, especially Juno. Her quality of attendant of Juno was particularly appropriate to the circumstances of discovery, as she was spotted following 3 Juno by less than an hour of right ascension.
Iris was observed occulting a star on May 26, 1995 and later on July 25, 1997. Both observations give a diameter of about 200 km.
External links
- "Discovery of Iris", MNRAS 7 (1847) 299 (http://adsabs.harvard.edu//full/seri/MNRAS/0007//0000299.000.html)
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| (For other objects and regions, see: Binary asteroids, Asteroid moons and the Solar system) |
| (For a complete listing, see: List of asteroids. For pronunciation, see: Pronunciation of asteroid names.) |
es:(7) Iris fr:7 Iris it:Iris (astronomia) nn:7 Iris pl:Iris (astronomia) pt:7 Iris