It is reportedly as big as Neptune and orbits a planet the size of Jupiter. It will take more observation with the Hubble to confirm it.
That planet, called Kepler-1625b, is one of thousands that scientists have recently detected around distant stars. Such an event is called a transit, and has been used to detect numerous exoplanets cataloged to date. Kepler uses the transit method, which involves measuring the regular dimming of a star's light caused by an orbiting planet passing in front of it, to indirectly detect exoplanets.
In a new paper published in Science Advances, Alex Teachey and David Kipping of Columbia University present their case for the first "exomoon", and it's some pretty wild stuff. The researchers found one instance in planet Kepler-1625b, of a transit signature with intriguing anomalies, suggesting the presence of a moon.
Kipping said "We saw little deviations and wobbles in the light curve that caught our attention".
So Kipping and Teachey studied the information from NASA's Kepler space telescope, an exoplanet chasing satellite.
Fast forward a year and throw in a mix of data from the Hubble Space Telescope and older data from the Kepler Space Telescope and the results look a lot more promising. This particular planet - or exoplanet - is about the same distance from its star as Earth is to the sun.More news: Canada Dairy Industry: New NAFTA a Bad Outcome
Kipping described this as "a moon trailing the planet like a dog following its owner on a leash".
In addition to this second dip in the light curve, Hubble provided compelling supporting evidence for the moon hypothesis by detecting the planet's transit more than an hour earlier than predicted.
Kepler 1625b was found to start its orbit over an hour early, a marker that something with generally solid gravity is pulling on it, substituting its focal point of gravity and influencing its orbit.
The possible moon was documented by Kepler, the powerhouse planet-hunting space telescope, when it cast a shadow by crossing in front of a star. This is called a "planetary wobble" and is caused by gravitational pull of another celestial body.
"A moon is an excellent explanation to the data at hand", Kipping said. "But we knew our job was to keep a level head testing every conceivable way in which the data could be tricking us until we were left with no other explanation".
Astronomers have discovered a large gaseous body, which is the size of Neptune and unlike any moon seen so far.More news: Brexit deal could be agreed within weeks, European Union chief says
Such gargantuan moons do not exist in our own solar system, where almost 200 natural satellites have been catalogued, said researchers from the Columbia University in the US.
"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", Kipping said. Its moon alone is estimated to be roughly the size and mass of Neptune, which has a radius four times that of Earth.
Moons are kind of the next frontier when it comes to understanding alien solar systems, says Bedell: "They capture our imagination".
This illustration by Dan Durda shows the exoplanet Kepler-1625-b with a hypothesized moon.
To date more than 3,000 exoplanets - worlds orbiting stars other than the Sun - but no "exomoons". Two Columbia University researchers presented their tantalising evidence for a moon Wednesday.More news: Meghan Markle And Prince Harry Visit A Sexual Violence And Abuse Charity