Kepler-1625b I is a possible extrasolar moon orbiting the extrasolar planet Kepler-1625b. If it is confirmed, then it may be the first extrasolar moon ever found. It was first detected in July 2017. The discovery of this moon suggests that the host planet is up to several Jupiter masses big, as the moon holds mass equal to that of the planet Neptune. It is possible that this extrasolar moon is habitable as it is located in the habitable zone of its host star, Kepler-1625, and has an equilibrium temperature of 253 K (-20 °C; -4 °F).
A reanalysis of the data published in April 2019 however has concluded that the data fits better with a planet-only model and that the moon may not exist.