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 2011, by radial velocity (NASA Exoplanet Archive).
Its planets
HD 20794 f — 2.3 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 650 days; about −58 °C, below freezing; found in 2025 by radial velocity.
HD 20794 e — 2 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 150 days; about 79 °C, between freezing and boiling; found in 2017 by radial velocity.
HD 20794 d — 2 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 90 days; about 120 °C, hotter than boiling water; found in 2011 by radial velocity.
HD 20794 b — 1.5 times Earth's width (estimated from its mass, not measured), about Earth-sized — probably rocky; its year lasts 18 days; about 390 °C, hotter than boiling water; found in 2011 by radial velocity.
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.