太陽系外縁天体
Meanings
1
trans-Neptunian object; TNO
Technical term in astronomy for any minor planet or dwarf planet orbiting the Sun beyond Neptune. Kuiper belt objects, scattered disc objects, and Oort cloud objects are also used.
Pluto is classified as one of the trans-Neptunian objects.
Observation of trans-Neptunian objects provides clues to the formation of the solar system.