Kepler-37b is the closest planet to Kepler-37. At the time of its discovery in February 2013, it was the smallest known exoplanet. At in diameter, it is slightly larger than the
Moon.
Discovery The Kepler-37 planets were discovered in September 2012 with the aid of
transit events detected by the
Kepler space telescope, and announced to the public in February 2013. However, he does not anticipate finding many planets as small as Kepler-37b due to the very small amount of light such planets obscure. Astronomer John Johnson of
Caltech university said the discovery would have been "unimaginable" a few years ago and that the telescope had revolutionized astronomers' picture of the universe. In 2014, a fourth planet with an orbital period of 51 days (Kepler-37e) was reported based on
transit-timing variations. Previously this signal was thought to be a false positive due to its low signal-to-noise ratio, and indeed later studies failed to detect either the transit or TTV signal. A study in 2021 again found that the TTV data disfavors the presence of planet e, and argued that it should be stripped of its "confirmed planet" status. A 2023 study modeled the system both with and without a planet candidate at 51 days. Based on the assumption that a planet with a circular orbit of about 51 days is present, marginal
radial velocity evidence was found for a sub-Neptune mass planet. Evidence of a longer-period planet candidate was also found. No additional planet has been confirmed, and the system remains with three confirmed planets. ==Notes==