29 Amphitrite (pronounced /ˌæmfɪˈtraɪti/, Greek: Αμφιτρίτη) is one of the largest S-type asteroids, probably third in diameter after Eunomia and Juno, although Iris and Herculina are similar in size.
It is probably not a fully solid body, since its density is too low for a solid silicate object and much lower than Eunomia or Juno. Its orbit is less eccentric and inclined than those of its larger cousins - being indeed the most circular of any asteroid discovered up to that point - and 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 more usually is around the binocular limit of +9.5.
Amphitrite was discovered by Albert Marth on March 1, 1854. It was his only asteroid discovery. It is named after Amphitrite, a sea goddess in Greek mythology.
A satellite is suspected based on the lightcurve data. 
1. ^ Tedesco, E. F. (March 1979). "Binary Asteroids: Evidence for Their Existence from Lightcurves". Science, New Series 203 (4383): 905-907.
2. ^ van Flandern, T. C.; Tedesco, E. F.; Binzel, R. P. (1979). "Satellites of asteroids". 'Asteroids': 443-465, Tucson, AZ: University of Arizona Press.