Astronomers Discover a Possible New Dwarf Planet in Our Solar System

The prospective planet measures somewhere between 600 and 1,500 kilometers in diameter and is located about 46 astronomical units from the sun (an astronomical unit being Earth’s approximate distance from the sun). For comparison, Pluto—which is also now considered a dwarf planet—orbits at an average distance of 40 astronomical units. Based on its location, ED138 belongs to the population of trans-Neptunian objects. According to its discoverers, it could be one of the brightest known objects of this type and also among the largest.

The difference between a planet and a dwarf planet is largely their environment. While both orbit the sun and have sufficient gravity to assume a nearly spherical shape, a planet has cleared its orbit of other bodies of comparable size.