The Themis or Themistian asteroid family is a Hirayama family (having similar orbital elements) of asteroids found in the outer portion of the asteroid belt, between the orbits of Mars and Jupiter. At a mean distance of 3.13 AU from the Sun, it is one of the more populous asteroid families. It consists of a well-defined core of larger asteroids and a surrounding region of smaller ones. This core group includes (and is named after) the asteroid 24 Themis, discovered on April 5, 1853 by Italian astronomer Annibale de Gasparis.