Trans-Neptunian Objects

Definition: Trans-Neptunian objects (TNOs) are any objects in the solar system that have an orbit beyond Neptune. Pluto is a trans-Neptunian object; another of the named Trans-Neptunian Objects is Varuna.

Total known: There are estimated to be perhaps 70,000 TNOs, each at least 100 km across, between 30 and 50 astronomical units from the Sun.