Ok, technically it’s not a new moon as it’s probably several billion years old but we didn’t know about it before, so it’s new to us! A team of researchers has just announced the discovery of a 150- to 250-mile-wide moon orbiting a dwarf planet in the Kuiper Belt named 2007 OR10. This distant, icy world is only 950 miles wide itself but it’s still the third largest dwarf planet, ranking behind Pluto and Eris in size.

The existence of the moon was first hinted at in observations by NASA’s Kepler telescope, which showed 2007 OR10 to be rotating suspiciously slowly for a KBO—45 hours as compared to a more typical under 24. After reviewing earlier Hubble observations of the object a moon was positively identified.

This discovery not only adds a new member to the Solar System’s family tree but also helps better understand the formation of KBOs.

“The discovery of satellites around all of the known large dwarf planets—except for Sedna—means that at the time these bodies formed billions of years ago, collisions must have been more frequent, and that’s a constraint on the formation models,” said Csaba Kiss of the Konkoly Observatory in Budapest, Hungary, lead author of the research. “If there were frequent collisions, then it was quite easy to form these satellites.”

Read the full article from NASA’s Goddard Space Flight Center here: Hubble Spots Moon Around Third Largest Dwarf Planet