Second Alien Moon Identified Is Much Like the First: Big and Strange

An artist's rendering shows a moon with a diameter roughly 2.6 times that of Earth orbiting a large gas giant planet in another solar system located about 5,700 light years from our solar system, in an undated handout illustration. Helena Valenzuela Widerstrom/Handout via Reuters

WASHINGTON—For only the second time, astronomers have detected what appears to be a moon orbiting a planet in another solar system. Just like the first time, this one has traits suggesting that such moons may differ greatly from those populating our solar system.

Data obtained by NASA’s Kepler space telescope before it was retired in 2018 indicated the presence of a moon 2.6 times the diameter of Earth orbiting a Jupiter-sized gas giant about 5,700 light-years away from our solar system in the direction of the Cygnus and Lyra constellations, scientists said on Thursday.