Strange space object: not a planet, orbiting not a star.

Mashable reported recently on a mysterious thing in space — a body we don’t yet have a name for. The category-defying object in CD-35 2722 system, about 73 light-years away, seems to be a Jupiter-sized exomoon that’s orbiting a brown dwarf star:

A brown dwarf is already something of a cosmic maverick — too large to be called a planet, too small to be a star. Experts sometimes refer to brown dwarfs as “failed stars” because they’re not quite massive enough to sustain hydrogen fusion in their cores.

That leaves researchers at a loss for what exactly to call this thing circling it. Because the object orbits a brown dwarf that is orbiting a star, it’s kind of an “exomoon,” they said, a satellite of a planet found outside the solar system.

“Being the third wheel in this system makes us want to call it a moon, even if it is nothing like the small, rocky moons we have in our system,” said Kevin Hoy, lead author of the study published in Nature, in a statement.

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“The exosatellite is clearly massive enough to be a planet, but it does not orbit a star,” Hoy said, “though it orbits an object that orbits a star.”

This is not the first time astronomers have found something that appears to be orbiting a brown dwarf, but previous detections involved objects that were much more separated. Because of that, whether those companions were moons or planets is debatable. In this case, the satellite orbiting CD-35 2722 B is hugging the brown dwarf so closely, it completes a trip every 170 days.

Researchers used the European Southern Observatory’s Very Large Telescope in Chile to make the discovery. Instead of taking a picture of the moon, the researchers used the observatory to see wobbles in the brown dwarf.

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Though a handful of exomoon candidates has been reported in scientific journals over the years, none of them have been confirmed yet. The CD-35 2722 B candidate also will require more observations before it gets such a designation, but Alice Zurlo, an astrophysicist at Universidad Diego Portales in Chile and a coauthor, is convinced this is the first “plausible” detection of an exosatellite.

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You can read more about the exosatellite here, in Nature.