Earth is the only place we know as yet where life exists and thrives. Other places that may have or had life are Mars, or the icy moons Europa and Enceladus. Outside the Solar System, however, it becomes even more of an open question. Exoplanets in the habitable zone are the subject of many existing searches, but over the last few years, researchers have had another target: exomoons.
If there are planets there must be moons. However, despite the numerous exoplanets discovered in the last couple of decades, no exomoons have been found yet, although some candidates have been observed that have intrigued researchers. This has led some to wonder if life could exist on such worlds. Dr Phil Sutton, a planetary scientist at the University of Lincoln, has written an interesting article about this very subject inspired by one of the most famous space franchises of all: Star Wars.
“From the cold desert moon Jedha and the forest moon Endor, to the rebel headquarters on the jungle moon Yavin 4, moons have played an important part of the Star Wars landscape,” Dr Sutton wrote in his post.
Habitable exomoons have not been the focus of much research but they are found so commonly in science fiction, Dr Sutton pointed out to IFLScience. And though the observations are not there yet, exciting theoretical studies suggest that these worlds could be habitable and perhaps there’s a better chance for them to host life.
“An interesting idea is that they have the potential to be habitable further away from their star than the habitable zone would normally allow. So they have a wider range of potential conditions that could be habitable in, possibly,” Dr Sutton told IFLScience.
There are some issues though. Planetary scientists don’t think that planets, even very large ones, would be able to hold on to moons as big as Earth if they were in the inner portion of their star system.
“A more likely scenario for a planet to have a sufficiently large moon that would be habitable, like those in Star Wars, is if they were smaller planets that came to close to the planet and were captured. We do know this can happen as Neptune captured a dwarf planet with an atmosphere, which is now known as Triton,” Dr Sutton explained.
Dr Sutton looks at the possibility of moons around J1407b, an exoplanet that famously has a ring system 200 times larger than Saturn’s own. The simulation he ran, unfortunately, suggests that moons are unlikely to exist in this system.
More observations are being conducted in this particular field, but there are obvious challenges. Only a small amount of Earth-size planets are known, and looking for something much smaller and more difficult to detect with the current method, might be looking for the proverbial needle in a haystack.
But you never know, an unlikely discovery might happen just when we least expect it.