Kepler-1388 b — 2.6 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 12 days; about 160 °C, hotter than boiling water; found in 2016 by transit.
Kepler-1388 c — 2.3 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 6 days; about 290 °C, hotter than boiling water; found in 2016 by transit.
Kepler-1388 d — 2.9 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 21 days; about 90 °C, between freezing and boiling; found in 2016 by transit.
Kepler-1388 e — 2.5 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 38 days; about 26 °C, between freezing and boiling; found in 2016 by transit.
NASA Exoplanet Archive, Planetary Systems Composite Parameters (fetched 2026-11-02). Composite values: where a planet's size or mass was not measured, the archive estimates it from the other.
This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.