First exomoon found? Neptune-sized world possibly spotted orbiting alien planet
Scientists may have bagged the first-ever exomoon.
NASA's Kepler and Hubble space telescopes have spotted evidence of a Neptune-size satellite orbiting the Jupiter-like planet Kepler-1625b, which lies about 8,000 light-years from Earth, a new study reports.
"We've tried our best to rule out other possibilities such as spacecraft anomalies, other planets in the system or stellar activity, but we're unable to find any other single hypothesis which can explain all of the data we have," co-author David Kipping, an astronomer at Columbia University in New York, told reporters earlier this week.

An artist’s illustration of the exoplanet Kepler-1625b with its large hypothesized moon. The pair have a similar mass and radius ratio to the Earth-moon system, but scaled up by a factor of 11. Credit: Dan Durda
Still, he and lead author Alex Teachey, also a Columbia astronomer, stressed that the observations don't constitute a definitive detection.
"We hope to re-observe the star again in the future to verify or reject the exomoon hypothesis," Kipping said. "And if validated, the planet-moon system — a Jupiter with a Neptune-sized moon — would be a remarkable system with unanticipated properties, in many ways echoing the unexpected discovery of hot Jupiters in the early days of planet hunting."
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