First possible exomoon may change scientists’ idea of what a moon is

(NewsNation) — Astronomers may have discovered the first moon outside of our solar system, and it may force them to reconsider the idea of what a “moon” is.

A new study published in Nature describes the discovery of a possible exomoon, but things get a little weird. Researchers noted the object could be an exomoon or it could be something else entirely that doesn’t fall neatly into the category of moon or planet.

While Earth’s singular moon is the most familiar, there are 891 moons orbiting planets and dwarf planets in our solar system, with more than 200 of those belonging to Saturn alone.

Given the numbers, it makes sense to assume planets in other solar systems travel with a similar entourage.

But while NASA has documented more than 6,000 exoplanets since the 1990s, when the first world outside our solar system was discovered, exomoons have remained elusive.

While using the Very Large Telescope — yes, that’s the real name — to study a star system labeled CD-35 2722, scientists discovered an object that could be the very first exomoon.

Located 73 light-years away from Earth, CD-35 2722 is a star with roughly half the mass of the sun. It’s orbited by a brown dwarf, also known as a “failed star.” Brown dwarfs are massive when compared to planets, clocking in at up to 80 times the mass of Jupiter, but small when compared to stars.

The newly discovered object appears moonlike, but instead of orbiting a planet the way moons in our solar system do, it orbits the brown dwarf.

That creates a three-layered system that doesn’t fit neatly into current concepts of what words like “planet” and “moon” actually mean.

The newly discovered object is large enough to be a planet but doesn’t orbit a star the way planets do. Instead, it orbits a nonplanet object that orbits a star. That’s what has led scientists to consider it the first (possible) exomoon.

Officially, the object has been labeled an exosatellite, with the discovery now raising questions about what a moon is and how it might be defined outside of our home system.

Researchers hope that the currently under-construction Extremely Large Telescope (also the official name) will help broaden the search for exomoons and exosatellites, giving more insight into the varied types of solar systems in the universe.

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