The Kepler-90 system has eight confirmed planets.
NASA’s Kepler space telescope found the system through the transit method, measuring tiny, repeating dips in Kepler-90’s brightness as planets passed across the star. The system’s eighth known planet, Kepler-90i, was announced on December 14, 2017, after a machine-learning analysis developed with Google helped identify a weak transit signal in archival Kepler data.
The planets are designated Kepler-90b through Kepler-90i; the missing letter a is normal because lowercase b is assigned to the first planet discovered around a star. Kepler-90 is an F-type star in the constellation Draco, about 855 parsecs away, and its system is notable for matching the Solar System’s total of eight known planets.
The arrangement also creates an interesting comparison: the six inner planets are smaller worlds ranging from super-Earths to mini-Neptunes, while the two outer planets are gas giants. A frequent error is answering seven, because the system was known as a seven-planet candidate before Kepler-90i was confirmed.