Asteroid 7, discovered in 1847 by the English astronomer John Russell Hind (1823–95). Iris is an S-class asteroid, of diameter 200 km. Its mean magnitude at opposition is 8.4; of the main-belt asteroids, only Vesta, Ceres, and Pallas can become brighter. Its orbit has a semimajor axis of 2.386 AU, period 3.68 years, perihelion 1.84 AU, aphelion 2.94 AU, and inclination 5°.5.
Subjects: Astronomy and Astrophysics.