Transit of Kepler-1625b and Suspected Moon

Transit of Kepler-1625b and Suspected Moon

About this image

This diagram represents Hubble Space Telescope photometric observations of the planet Kepler-1625b passing in front of its parent star — called a transit. The planet blocks a small fraction of the star's light and this is recorded on a light curve (bottom green line) as a slight dip in the star’s brightness. After the planet's 19-hour-long transit was completed, astronomers noted a second, smaller dip in the light curve about three and a half hours later (panel 4). (Due to observing constraints Hubble was not able to record the full event.) The second dip is interpreted as the signature of a moon trailing the planet. The moon is estimated to be as big as the planet Neptune. The inclination of the candidate moon's orbit is just one of a broad range of possible inclinations that are consistent with the data. Astronomers hope to repeat this observation to confirm the moon's existence. If follow-up observations are successful, this would be the first moon discovered outside of our solar system.

Exoplanets, Hubble Telescope, Illustrative, Kepler, Moons


NASA, ESA, D. Kipping (Columbia University), and A. Feild (STScI)