the hunt for exomoons is on

The race for the exomoon has just been included in the program of the third observation cycle of the James Webb telescope: moons around other planets which revolve around other stars. They must exist, but they are very difficult to see.

Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon, speaks to us today about new program of the James Webb Space Telescope which has just been made public.

franceinfo: In the long list of targets that this space telescope will observe, there are exomoons: the moons which revolve around planets, which revolve around stars other than ours?

Mathilde Fontez: Yes, the distant moons,like Pandora in Avataror the moon Endor – the one where the Ewok live in Star Wars. That’s fiction. But in reality, that’s it, the hunt for exomoons is on. We had to wait for the third cycle of the James Webb telescope.

It must be said that competition is fierce to use this telescope, since it was put into orbit in 2021, to observe space with unprecedented precision and power. Nearly 2000 observation programs were submitted with only 250 selected. And among them: 5 programs dedicated to exomoons.

The Webb telescope will target planets to detect moons?

Yes, for example a planet the size of Jupiter, it’s called Kepler-167 e, which orbits 1100 light years from Earth – it could have one or more large moons. Or the TOI-700 system, with small planets, and perhaps moons like ours…

Until now we have never seen an exomoon. It’s not for lack of trying: there are candidates: LThe latter was discovered in 2022, by an American team, around a star similar to the Sun. It would be a giant moon the size of our Jupiter. If this signal is real. Telescopes until then were not sensitive enough to be sure that it was not background noise, or a variation in the light of the star.

Is it certain that these exomoons exist?

Astrophysicists are convinced of this. Just look at our system: there are more than 200 moons in the solar system. The Earth only has one, but the giant Jupiter has 95, Saturn has 146. More than 5,000 exoplanets and more than 5,000 planets around other stars have been discovered in space. Of all kinds, gas giants, small ones like Earth, icy ones like Neptune or Uranus.

There is no reason why our system should be the only one to have moons. It remains to detect them. The James Webb telescope has been awaited for years by the community of exomoon researchers to lead this quest. Will it be precise enough to detect exomoons? Response in a few months.

The five programs of the James Webb telescope devoted to exomoons