Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.
Facts
Kepler-281 d has an equilibrium temperature between −50 and +50 °C.
How it was found
First planet found in 2014, by transit (NASA Exoplanet Archive).
Its planets
Kepler-281 c — 5.3 times Earth's width, Neptune-sized; its year lasts 36 days; about 240 °C, hotter than boiling water; found in 2014 by transit.
Kepler-281 d — 5.9 times Earth's width, Neptune-sized; its year lasts 150 days; about 48 °C, between freezing and boiling; found in 2021 by transit.
Kepler-281 b — 2.8 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 15 days; about 420 °C, hotter than boiling water; found in 2014 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.