7 Iris is a large main-belt asteroid. Among the S-type asteroids, it ranks fifth in geometric mean diameter after Eunomia, Juno, Amphitrite and Herculina.
Its bright surface and small distance from the Sun make Iris the fourth brightest object in the asteroid belt after Vesta, Ceres, and Pallas. But at typical oppositions it marginally outshines the larger though darker Pallas. It has a mean opposition magnitude of +7.8, comparable to that of Neptune, and can easily be seen with binoculars at most oppositions. At rare oppositions near perihelion Iris can reach a magnitude of +6.7 (next time on October 31, 2017 reaching a magnitude of +6.9), which is as bright as Ceres ever gets; reports of it being seen without optical aid are unverified.
- 580 Views
Category: Astronomical Symbols.
More symbols in Asteroids:
Asteroids are minor planets (small Solar System bodies and dwarf planets) that are not comets, especially those of the inner Solar System. They have also been called planetoids, especially the larger… read more »
More symbols in Astronomical Symbols:
Astronomical symbols are symbols used to represent various celestial objects, theoretical constructs and observational events in astronomy. The earliest forms of these symbols appear in Greek papyri … read more »