A pair of astronomers believes they’ve found a moon orbiting a planet outside our Solar System — something that has never before been confirmed to exist.
Though they aren’t totally certain of their discovery yet, the find opens up the possibility that more distant moons are out there. And that could change our understanding of how the Universe is structured.
The astronomy team from Columbia University found this distant satellite, known as an exomoon, using two of NASA’s space telescopes.
They first spotted a signal from the object in data collected by the planet-hunting telescope Kepler, and then they followed up with the Hubble Space Telescope, which is in orbit around Earth.
Thanks to the observations from these two spacecraft, the team suspect this moon orbits around a Jupiter-sized planet located about 4,000 light-years from Earth. And this planet, dubbed Kepler-1625b, orbits around a star similar to our Sun.
Scientists have strongly believed for decades that moons exist outside our Solar System, but these objects have remained elusive for scientists up until now.
There have been just a couple of candidates that astronomers have speculated about in the past, but nothing has been confirmed.
That’s because moons are thought to be too small and too faint to pick up from Earth. However, this suspected exomoon, detailed today in the journal Science Advances, is particularly large, about the size of Neptune, making it one of the few targets that our telescopes can detect.
“You can make the argument that this is the lowest hanging fruit,” Alex Teachey, an astronomy graduate student at Columbia University and one of the lead authors on the paper said.
“Because it is so large, in some ways, this is the first thing we should detect because it is the easiest.”
Teachey argues that finding more moons outside our Solar System will change our understanding of how planetary systems formed thousands of light-years away.
Our cosmic neighborhood is filled with moons, and they explain a lot about how our planets came to be. Exomoons could tell similar tales.
However, none of our moons come close to the size of this one, which creates a puzzle for astronomers.
“Because it is so unusual, or at least has not been anticipated largely by the community, this poses new challenges to explain it,” says Teachey. “How do you get something like this?”
It was only a few decades ago — in the late 1980s and early 1990s — that astronomers confirmed the existence of planets outside our Solar System.
Since then, thousands of these distant worlds, known as exoplanets, have been confirmed by spacecraft like Kepler and other telescopes.
Perhaps the most popular way to find exoplanets is by staring at stars, waiting for them to flicker. When a planet crosses “in front” of its host star, it dims the stars’ light ever so slightly.
These dips in brightness can be used to determine how big a planet is and the kind of orbit it’s on.
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