Amphitrite

Amphitrite (/ˌæmfɪˈtraɪtiː/ am-fi-TRY-tee; minor planet designation: 29 Amphridite) is one of the largest S-type asteroids, approximately 200 kilometers (124 miles) in diameter, and probably third largest after Eunomia and Juno, although Iris and Herculina are similar in size.

Discovery

Amphitrite was discovered by Albert Marth on March 1, 1854, at the private South Villa Observatory, in Regent's Park, London. It was Marth's only asteroid discovery. Its name was chosen by George Bishop, the owner of the observatory, who named it after Amphitrite, a sea goddess in Greek mythology.

Characteristics

Amphirite's orbit is less eccentric and inclined than those of its larger cousins; indeed, it is the most circular of any asteroid discovered up to that point. As a consequence, it never becomes as bright as Iris or Hebe, especially as it is much further from the Sun than those asteroids. It can reach magnitudes of around +8.6 at a favorable opposition, but usually is around the binocular limit of +9.5.

Asteroid 29 Amphitrite will again be visible at 13:24 on Sunday, the 13th of October 2019. It will be convenient to observe 29 Amphitrite from the constellation Pisces, well above Sydney's horizon for the greater part of the night. 

In 2007, James Baer and Steven R. Chesley estimated Amphitrite to have a mass of 1.9×10¹⁹ kg. A more recent estimate by Baer suggests it has a mass of 1.18×10¹⁹ kg.

A satellite of the asteroid is suspected to exist, based on lightcurve data collected by Edward F. Tedesco. In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.