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 2014, by transit timing variations and transit and radial velocity (NASA Exoplanet Archive).
Its planets
Kepler-139 f — 6.7 times Earth's width (estimated from its mass, not measured), Neptune-sized; its year lasts 360 days; found in 2025 by transit timing variations.
Kepler-139 c — 3.4 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 160 days; about 77 °C, between freezing and boiling; found in 2014 by transit.
Kepler-139 e — 14 times Earth's width (estimated from its mass, not measured), a giant, Jupiter-sized or more; its year lasts about 6 Earth years; about −120 °C, below freezing; found in 2023 by radial velocity.
Kepler-139 b — 2.9 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 16 days; about 480 °C, hotter than boiling water; found in 2014 by transit.
Kepler-139 d — 1.7 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 7 days; about 700 °C, hotter than boiling water; found in 2023 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.