Yesterday (Oct. 3), researchers announced they had spotted evidence of a Neptune-size moon circling the planet Kepler-1625b, which is about three times more massive than Jupiter.
Like the exoplanets we're so keen to uncover, these moons orbiting planets in other star systems could lead us to extraterrestrial life-or at least a deeper understanding of outer space.
Researchers Alex Teachey and David Kipping evaluated 284 planets outside our solar system that had already been discovered by Nasa's Kepler Space Telescope. Its moon alone is estimated to be roughly the size and mass of Neptune, which has a radius four times that of Earth.
The team behind this intriguing discovery, researched more than 250 planets outside our solar system using the space telescope NASA Kepler.
"If confirmed by follow-up Hubble 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".
The celestial object has a diameter of about 49,000 km, more than nine times the size of Jupiter's Ganymede, which is the largest moon in the solar system.
Spotting an exomoon is done in largely the same way, and if the team's measurements are on point we're looking at an absolutely enormous moon and an even larger host planet. This value is close to the mass-ratio between the Earth and its moon.
Researchers detect exoplanets by observing the reduction in the brightness of the star they orbit.
As a planet passes in front of its host star, it blocks some of the light being observed by planet-hunting probes like Kepler. When planets have large moons, the two objects orbit a common center of gravity. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.
The astronomers are uncertain how this potential moon might have formed, given its size.
"We noticed a certain refractive index, and deviations in the light curve that caught our attention", explained KPMG.
On 28 and 29 October 2017, the scientists sent it to Kepler 1625 and watched it for 40 hours, including the 19-hour transit of the planet on background stars.
This decrease in dimness is consistent with "a moon trailing the planet like a dog following its owner on a leash", Kipping said.
Because their transit signals are weaker than those of planets and their positions change as they orbit their parent planets.
Clearly, an exomoon may contribute an additional transit signal of its own, but for an object comparable in size to the Earth's moon, the extra dimming will only amount to around ten parts per million - making it hard to detect.
Future searches will target Jupiter-sized planets that are farther from their star than Earth is from the Sun. "When we look for an Earth twin, I think one of the most obvious things you might ask is, 'Does it have a moon twin, ' because that seems to have a large influence", he notes".