Hilda (minor planet designation: 153 Hilda) is a large asteroid in the outer main belt, with a diameter of 170 km.^[1] The spectrum matches that of a P-type asteroid.^[4] It was discovered by Johann Palisa on 2 November 1875, from the Austrian Naval Observatory at Pula, now Croatia.^[1] The name was chosen by the astronomer Theodor von Oppolzer, who named it after one of his daughters.^[5]

Hilda gives its name to an asteroid group called the Hilda group (or Hildas for short). It is not a true asteroid family, since the members are not physically related, but rather share similar orbital elements. The Hildas are locked in a 2:3 orbital resonance with Jupiter;^[6] since Jupiter takes 11.9 years to orbit the Sun while Hilda takes 7.9 years,^[1] Jupiter orbits the Sun twice for every 3 orbits that Hilda completes. There are over 1,100 other objects known to be in a 2:3 resonance with Jupiter.^[6]

The orbital plane of 153 Hilda is inclined at an angle of 7.82° to the plane of the ecliptic. It has an orbital eccentricity (ovalness) of 0.13971.^[1] Multiple light curves of the asteroid provide a consistent rotation period of approximately 5.9585 h^[7]