First ‘Exomoon’ Possibly Found: Hubble Spots Alien Moon The Size Of Neptune 8,000 Light-Years From Earth
In a stunning discovery, astronomers may have stumbled upon the first-ever alien moon, or “exomoon,” to be found orbiting a planet outside of our solar system, NASA announced earlier today.
The credit goes to astronomers Alex Teachey and David Kipping from Columbia University in New York, who used the Hubble Space Telescope to zero in on what seems to be a massive alien moon orbiting a giant planet 8,000 light-years away.
This is “the first compelling evidence for a moon outside our own solar system,” states the Hubble Space Telescope website, noting that scientists have long waited to make such a detection. While the first discovery of an exoplanet occurred 30 years ago, no one has ever managed to uncover strong evidence of an exomoon until now.
The remarkable find, described in a study just published in the journal Science Advances, points to a Neptune-sized exomoon around an exoplanet known as Kepler-1625b, which orbits a star codenamed Kepler-1625 located in the constellation of Cygnus (“the Swan”).
As the Inquisitr previously reported, this particular object has been an exomoon candidate since 2016, when the two astronomers came across the first clues that Kepler-1625b could be orbited by an alien moon. At the time, the researchers examined 284 planet candidates found by the Kepler Space Telescope, all of which stood a good chance of hosting a natural satellite.
The original paper, available on the arXiv server, singled out the exoplanet and its suspected exomoon, dubbed Kepler-1625b-i, as the most promising of the bunch.
Did the @NASAHubble Space Telescope confirm the first moon orbiting a planet outside our solar system?
Watch & find out: https://t.co/eXJEDTLt73 pic.twitter.com/02MHMUL00M
— NASA (@NASA) October 3, 2018
Their latest research revisited the old Kepler data, taking an in-depth look at the Kepler-1625 star with the Hubble telescope. The new paper makes a strong case that the stellar system’s only known exoplanet could have its very own moon based on data recorded via the transit method.
This method searches for potential alien worlds by measuring the tiny dips in brightness they cause whenever they pass in front of (transit) a star, blocking its light.
#Hubble finds compelling evidence for a moon outside the Solar System. The data indicate an #exomoon the size of #Neptune, in a stellar system 8000 light-years from Earth. Read more at the link below. https://t.co/dWuumJfVC2
Credit: @NASA , @ESA pic.twitter.com/uPuGROCGgf— HUBBLE (@HUBBLE_space) October 3, 2018
The team logged in about 40 hours of Hubble time to take a better look at Kepler-1625 and managed to observe not one, but two dips in starlight brightness during one of the exoplanet’s 19-hour transits.
According to the video below, released by Hubble officials a few hours ago, the first dip in light brightness was seen as Kepler-1625b passed in front of its parent star. Meanwhile, the second occurrence was significantly smaller and was recorded about 3.5 hours later.
This hints at a smaller object trailing behind the exoplanet, possibly the first exomoon to ever be discovered.
“It was definitely a shocking moment to see that light curve — my heart started beating a little faster and I just kept looking at that signature,” Kipping said in a statement.
Another clue that signals the presence of a potential exomoon around Kepler-1625b has to do with the timing of the exoplanet’s transit. As Teachey explains in the video below, the team previously examined the exoplanet during three separate transits of its host star. The new Hubble observations recorded Kepler-1625b transiting “a full 78 minutes earlier than we anticipated,” said Teachey, suggesting a wobble in the exoplanet’s trajectory.
The wobble could be explained by the presence of an exomoon, in the same way that our moon caused Earth to wobble as it orbits the planet, shows NASA.
This extraordinary discovery is made even more exciting by the sheer size of the suspected exomoon. The gargantuan moon has a diameter comparable to that of Neptune and is nothing like the moons circling the planets in our solar system.
The parent exoplanet is equally unusual, dwarfing the planets inhabiting our own system. Kepler-1625b is a gas giant weighing several times the mass of Jupiter, our solar system’s largest planet. The potential exomoon that could be floating around it is estimated to weigh just 1.5 percent the mass of this imposing planet.
The same mass-ratio can be observed in the case of Earth and our own moon, notes NASA. But while both our planet and its natural satellite are rocky, Kepler-1625b and Kepler-1625b-i are gaseous, which means that the alien moon was born in a completely different way than the accretion of leftover planetary material that gives rise to rocky moons.
“This may yield new insights into the development of planetary systems and may cause astronomers to revisit theories of how moons form,” said Teachey.
Although the exomoon is yet to be confirmed, as the allotted Hubble time ended before the astronomers could measure the full transit of the moon candidate, this is the closest that anyone has ever gotten to detecting a moon outside of our solar system.
“If confirmed, Kepler-1625b-i will certainly provide an interesting puzzle for theorists to solve,” said Kipping.
