The discovery of an Exomoon potential raises hopes for real life Pandora or Endor

The potential discovery of a huge exomoon around a giant gas planet arouses some fantasies of science fiction.

Yesterday (Oct. 3), researchers reported spotting traces of a Neptune-sized moon surrounding the Kepler-1625b planet, about three times more massive than Jupiter.

The candidate moon, which has yet to be confirmed by later observations, is probably gaseous and therefore not an excellent bet to accommodate life as we know it, said the scientists. But there could be livable exomoons out there, waiting to be found.

"We hope that someday we could really find something that looks like a true analogue of the Earth in a moon," Teachey told reporters during a conference call Monday (Oct. 1). Teachey, a third-year student at Columbia University in New York, was the first author of the research announcing the potential of the moon.

"It's more like what people think when they think of a Pandora" Avatar "," he added.

In James Cameron's movie "Avatar" dating back to 2009, humans visit Pandora, the fifth moon of the (fictional) gas giant Polyphemus, described as orbiting around the actual star Alpha Centauri A. (Do not confuse the world "Avatar" with the real life of Pandora, which is a small moon of Saturn very cratered.) The film describes Pandora as a rocky world, just smaller than the Earth in terms of mass and radius and endowed with a unusual life.

But Teachey said that Pandora was not his favorite world for exomoons. "I'm in favor of Endor myself," he says. "I'm more of a fan of" Star Wars ".

Endor represents about a third of the Earth's diameter and is covered with dense forests. Its most famous inhabitants are the ferocious but adorable Ewoks, although it is home to several other species of the "Star Wars" universe. Unlike Pandora, Endor orbits not one but two suns.

Teachey and co-author of the study, David Kipping, of Columbia, were very cautious about their potential discovery, stressing that they remained focused on confirming the existence of the I & # 39; exooon around Kepler-1625b rather than on his life potential. (Although the planet and the moon seem to orbit in the "habitable zone" of their star)

"To be honest, we have never really worried about habitability, just because they're both gas giants, so it's not something that has cost us much effort or time, "Kipping said at Monday's teleconference.

However, the researchers made some interesting observations, which they have quite speculative.

For example, the star at the center of the system is about 10 billion years old, about twice the age of the Earth's sun, and so is nearing the end of its life. This means that this star, and the planet and moon on which it shines, were probably a lot colder in the past, said Kipping. As the star has warmed over the past millennia, the new moon could also have heated up, causing an expansion of its atmosphere. This could have produced a rocky moon with an inflated atmosphere that resembles an object the size of Neptune.

"It is certainly possible that the moon has a relatively low mass," said Kipping. "Some of our models even allow Earth's mass for the moon."

Such a natural satellite would be more in line with the fictional worlds of "Avatar" and "Star Wars".

Another possibility is that the moon, whatever its size, has moved away from its planet over the centuries. Today, the exomoon lies about 1.9 million miles (3 million kilometers) from Kepler-1625b. However, scientists know that the Earth's moon is progressively moving away from our planet at a rate of about 4 centimeters (1.5 inches) per year.

The exomoon candidate – whose signs were spotted by NASA's Kepler and Hubble space telescopes – was also able to move away from his planet over time, so that it could have been much closer in the past, Kipping said.

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