We have now confirmed the existence of more than 4,000 exoplanets or planets outside our solar system that teach us about how planets and systems form and can even help us locate other habitable worlds. However, one object that is more difficult to see is the exo-moon. Astronomers believe it is very likely that moons exist outside our solar system, but because they are generally so small, they are extremely difficult to identify. However, astronomers at Columbia University believe they may have located evidence for the exo-moon.
The potential exo-moon, which is very large and orbits a Jupiter-sized planet called Kepler 1708b, is 5,500 light-years away. This is the second exo-moon candidate discovered by the same team, led by David Kipping. “Astronomers have found over 10,000 exoplanet candidates so far, but exo-moons are much more difficult,” Kipping said in statement. “They are terra incognita.”
Kipping and his team looked at archival data from NASA’s Kepler telescope and focused on the coldest gas giants. They chose to focus on these exoplanets because the equivalent planets in our solar system, Jupiter and Saturn, have many moons orbiting them.
They searched data on 70 planets before finding the signal of one candidate for exo-moon. The large size meant that this signal stood out, and if more candidates were discovered in the future, they probably wouldn’t be as large. “The first discoveries in any poll will generally be freaks,” explained Kipping. “The large ones that are simply the easiest to detect with our limited sensitivity.”
Astronomers will need to collect more data before they can confirm whether a candidate is in fact an excrescent or if it is just a weirdness in the data. It is possible that the signal could have been caused by the planet’s interaction with its star or the noise from the Kepler instrument. For now, Kippling and his colleagues will continue to look for further evidence as to whether it is indeed a moon outside our solar system.
The research is published in the journal Astronomy of Nature.