The major moons in our Solar System could contain some objects with candidates for potentially having orbiting moons of their own. If many of these moons were situated in different locations, astronomers would define them as planets. Based on where they are, the seven largest non-planets in the Solar System are all moons.(EMILY LAKDAWALLA, VIA PLANETARY.ORG/MULTIMEDIA/SPACE-IMAGES/CHARTS/THE-NOT-PLANETS.HTML. THE MOON: GARI ARRILLAGA. OTHER DATA: NASA/JPL/JHUAPL/SWRI/UCLA/MPS/IDA. PROCESSING BY TED STRYK, GORDAN UGARKOVIC, EMILY LAKDAWALLA, AND JASON PERRY)

These Are The 10 Largest Non-Planets In Our Solar System

Only 8 worlds make the astronomical cut as planets. Here are the 10 fascinating bodies that didn’t make it.

Astronomically, bodies within the Solar System must achieve three criteria in order to gain the much-vaunted status of planet:

1. Gravitationally pull themselves into a spheroidal shape, where they obtain hydrostatic equilibrium,
2. Orbit the Sun in an ellipse and no other smaller, parent body,
3. and clear their orbit of any substantially-massed objects.

The eight planets of our Solar System and our Sun, to scale in size but not in terms of orbital distances. Note that these are the only eight objects that meet all three of the planetary criteria as set forth by the IAU. (WIKIMEDIA COMMONS USER WP)

In our Solar System, only eight worlds make the cut given those criteria. The four rocky planets (Mercury, Venus, Earth, Mars) and the four gas giant worlds (Jupiter, Saturn, Uranus, Neptune) are the only ones that can be called planets under these definitions. Everything else, no matter how large or massive, fails on one of the latter two criteria.

If you judge whether an object is a planet or not by the IAU’s criteria, that satisfies planets in our solar system, but no others. However, by looking at a distant world’s mass, orbital parameters, and the age of the solar system, you can reproduce the IAU’s definition for 99+% of the worlds we know of. (MARGOT (2015), VIA ARXIV.ORG/ABS/1507.06300)