Astronomers think they might have found the first moon outside our own solar system – the first exomoon.

If this is true it would not only be a once-in-a-generation success for the scientists, it would also question our whole understanding of how moons come into existence.

Kepler-1625b-i would have 1,5% of the mass of his planet (like the earth-moon duo), but since the enormous planet Kepler-1625b is several times the size of Jupiter, the moon would be gaseous and have the mass of Neptun, hence the name of “Neptmoon”, as his potential discoverers have named him.

Potential?

Yes, since the existence of Neptmoon is still not proven. The only way is to measure the movements of the planet in front of the sun, darkening the sun a bit. And of course there could be other explanations for the observed light change, like a different planet being there in just the right (or wrong) time.

Until now there have been only two observations, and only one with the vastly more precise Hubble. The scientists hope to have a decisive look at the matter in one “year”, 287 days, when the planet and his potential moon will cross the sun again.

For the time being they can have a go on the hard to crack nut how this moon can even exist. Because a moon of this size cannot be explained with current theories, which might be the main reason why the scientists are still skeptic.

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