Astronomers may have spotted one of the first exomoons

We have now confirmed the existence of more than 4,000 exoplanets, or planets outside our solar system, which teach us how planets and systems form and may even help us locate other habitable worlds. However, a more difficult object to spot is an exomoon. Astronomers think it’s very likely that moons exist outside our solar system, but because they’re usually so small, they’re extremely difficult to identify. However, astronomers at Columbia University believe they have found evidence of an exomoon.

The potential exomoon, which is very large and orbits a Jupiter-sized planet called Kepler 1708b, is located 5,500 light-years away. This is the second candidate exomoon discovered by the same team, led by David Kipping. “Astronomers have found over 10,000 exoplanet candidates so far, but exomoons are much more difficult,” Kipping said in a declaration. “They are terra incognita.”

Kipping and his team looked at archival data from NASA’s Kepler telescope and focused on the coldest gas giant planets. They chose to focus on these exoplanets because the equivalent planets in our solar system, Jupiter and Saturn, both have many moons orbiting them.

They scoured data from 70 planets before finding the signal from the only exomoon candidate. Being oversized meant that this signal stood out, and if other candidates are discovered in the future, they probably won’t be that important. “The first detections in any investigation will usually be the crackpots,” Kipping explained. “The big ones that are just the easiest to detect with our limited sensitivity.”

Astronomers will need to collect more data before they can confirm whether the candidate is in fact an exomoon, or if it’s just a quirk in the data. It is possible that the signal is caused by the interaction of the planet with its star or by the noise of the Kepler instrument. So for now, Kippling and his colleagues will continue to search for more evidence to find out if this is in fact a moon beyond our solar system.

The research is published in the journal natural astronomy.