Hilda family

The Hilda or Hildian asteroids are a dynamical group of asteroids in a 3:2 orbital resonance with Jupiter. Hildas move in their elliptical orbits so that their aphelia put them opposite Jupiter, or 60 degrees ahead of or behind Jupiter at the L₄ and L₅ Lagrangian points. Over three successive orbits each Hilda asteroid passes through all of these three points in sequence. A Hilda's orbit has a semi-major axis between 3.7 AU and 4.2 AU, an eccentricity less than 0.3, and an inclination less than 20°. Two collisional families exist within the Hilda group: the Hilda family and the Schubart family. The namesake is 153 Hilda, discovered by Johann Palisa in 1875. There are more than 1,100 known Hilda asteroids including unnumbered objects.