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IAU Minor Planet Center

Minor Planet Center

Unusual Minor Planets

The lists of unusual objects accessible from this page include both close-approach and distant objects. Note that the definitions of Aten, Apollo and Amor objects differ between different groups. The definitions used here are that: Atens have semimajor axes less than 1.0 AU; Apollos have perihelion distances less than 1.0 AU and semimajor axes greater than 1.0 AU; and Amors have perihelion distances between 1.0 and 1.3 AU. Centaur objects have perihelia beyond the orbit of Jupiter and semimajor axes inside the orbit of Neptune. Transneptunian objects have orbits with semimajor axes beyond the orbit of Neptune--some of these objects, generally assumed to be in librations with Neptune, have perihelion distances inside the orbit of Neptune.


At the present time, these lists contain entries for the following numbers of objects:

  • 7114 close approach
  • 1433 distant objects
  • 340 other unusual objects
More specifically:
  • 592 Atens
  • 3574 Apollos
  • 2948 Amors
  • 284 Centaurs and Scattered-Disk Objects
  • 1149 transneptunians

The close-approacher lists are here:

The distant-object lists are here (ordered by designation):

The Trojan lists are here (ordered by designation):

Here is a list of other unusual objects that do not fit into any of the above categories.

The 1137 Potentially Hazardous Asteroids (the minor planets with the greatest potential for close approaches to the earth) include those objects with H brighter than or equal to V = 22.0 and an Earth MOID (see explanation) less than 0.05 AU.


This page was last updated on 2010 Aug. 27.


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