704 Interamnia - Characteristics

Characteristics

Although Interamnia is the largest asteroid after the "big four", it is a very little-studied body. It is easily the largest of the F-type asteroids, but there exist very few details of its internal composition or shape, and no lightcurve analysis has yet been done to determine the ecliptic coordinates of Interamnia's poles (and hence its axial tilt). Its apparently high bulk density (though subject to much error) suggests an extremely solid body entirely without internal porosity or traces of water. This also strongly suggests that Interamnia is large enough to have fully withstood all the collisions that have occurred in the asteroid belt since the Solar System was formed.

Its very dark surface and relatively large distance from the Sun means Interamnia can never be seen with 10x50 binoculars. At most oppositions its magnitude is around +11.0, which is less than the minimum brightness of Vesta, Ceres or Pallas. Even at a perihelic opposition its magnitude is only +9.9, which is over four magnitudes lower than Vesta.

Its orbit is slightly more eccentric that that of Hygiea (15% versus 12%) but differs from Hygiea's in its much greater inclination and slightly shorter period. Another difference is that Interamnia's perihelion is located on the opposite side from the perihelia of the "big four", so that Interamnia at perihelion is actually closer to the Sun than Ceres and Pallas are at the same longitude. It is unlikely to collide with Pallas because their nodes are located too far apart, whilst although its nodes are located on the opposite side from those of Ceres, it is generally clear of Ceres when both cross the same orbital plane and a collision is again unlikely.