First Evidence of Moon outside our solar system: Astronomers

New York: Using the Hubble Space Telescope and the Kepler Space Telescope, astronomers have found the first compelling evidence for a Neptune-sized moon orbiting a giant gas planet 8,000 light-years away. The detection of the candidate exomoon — moons orbiting planets in other star systems — is unusual because of its large size, comparable to the diameter of Neptune. Such gargantuan moons do not exist in our own solar system, where nearly 200 natural satellites have been cataloged.

Astronomers first found exoplanets — planets outside our own Solar System — 30 years ago. However, the search for moons orbiting these exoplanets was not successful — until today. “This would be the first case of detecting a moon outside our solar system,” said David Kipping, Assistant Professor at the Columbia University in New York. “If confirmed by follow-up observations, the finding could provide vital clues about the development of planetary systems and may cause experts to revisit theories of how moons form around planets,” he added.

To look for exomoons, the team analyzed data from 284 Kepler-discovered planets that were in comparatively wide orbits, with periods greater than 30 days, around their host star. The observations measured the momentary dimming of starlight as a planet passed in front of its star, called a transit. The researchers found one instance, in Kepler 1625b, that had intriguing anomalies.

The moon is estimated to be only 1.5 percent the mass of its companion planet, which itself estimated to be several times the mass of Jupiter. This value is close to the mass-ratio between the Earth and its moon. Like its moon, Kepler-1625b is also bigger than its counterparts in the Solar System. The exoplanet is a gas giant, several times more massive than Jupiter. (IANS)