Mars-crosser in the context of Mars trojan

Robert Burnham Jr. (June 16, 1931 – March 20, 1993) was an American astronomer, best known for writing the classic three-volume Burnham's Celestial Handbook. He discovered numerous asteroids, including the Mars crossing asteroid 3397 Leyla, and six comets.

Burnham's late years were tragic; he died destitute and alone. However, he is remembered by a generation of deep sky observers for his unique contribution to astronomy, the Celestial Handbook. The main-belt asteroid 3467 Bernheim was named in his honor.

A distant minor planet, or distant object, is any minor planet found beyond Jupiter in the outer Solar System that is not commonly thought of as an "asteroid". The umbrella term is used by IAU's Minor Planet Center (MPC), which is responsible for the identification, designation and orbit computation of these objects. As of January 2025, the MPC maintains 6101 distant objects in its data base.

Most distant minor planets are trans-Neptunian objects and centaurs, while relatively few are damocloids, Neptune trojans or Uranus trojans. All distant objects have a semi-major axis (average distance from the Sun) greater than 6 AU. This threshold, which is just beyond the orbit of Jupiter (5.2 AU), ensures that the vast majority of "true asteroids" – such as the near-Earth, Mars-crosser, main-belt and Jupiter trojan populations – are excluded from the distant minor planets.

3552 Don Quixote, provisionally designated 1983 SA, is an exceptionally eccentric asteroid, classified as a near-Earth object of the Amor group, Mars-crosser and Jupiter-crosser, as well as a weakly active comet.