Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.
How it was found
First planet found in 2013, by transit (NASA Exoplanet Archive).
Its planets
Kepler-238 d — 3.1 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 13 days; about 620 °C, hotter than boiling water; found in 2014 by transit.
Kepler-238 f — 2 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 50 days; about 300 °C, hotter than boiling water; found in 2013 by transit.
Kepler-238 b — 1.7 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 2 days; about 1,400 °C, hot enough to melt rock; found in 2014 by transit.
Kepler-238 c — 2.4 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 6 days; about 870 °C, hotter than boiling water; found in 2014 by transit.
Kepler-238 e — 5.6 times Earth's width, Neptune-sized; its year lasts 24 days; about 460 °C, hotter than boiling water; found in 2013 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.