Generally Hygiea's properties are the least known out of the "big four" objects in the main belt. Its orbit is much closer to the plane of the ecliptic than those of Ceres, Pallas or Interamnia, but is less circular than Ceres or Vesta with an eccentricity of around 12%. Its perihelion is at a quite similar longitude to those of Vesta and Ceres, though its ascending and descending nodes are opposite the corresponding ones for those objects. Although its perihelion is extremely close to the mean distance of Ceres and Pallas, a collision between Hygiea and its bigger companions is impossible because at that distance they are always on opposite sides of the ecliptic. At aphelion Hygiea reaches out to the extreme edge of the asteroid belt at the perihelia of the Hilda family which is in 3:2 resonance with Jupiter.