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 2020, by radial velocity (NASA Exoplanet Archive).
Its planets
HD 158259 d — 2.2 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 5 days; found in 2020 by radial velocity.
HD 158259 b — 1.3 times Earth's width, about Earth-sized — probably rocky; its year lasts 2 days; about 1,200 °C, hot enough to melt rock; found in 2020 by radial velocity.
HD 158259 c — 2.2 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 3 days; found in 2020 by radial velocity.
HD 158259 e — 2.3 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 8 days; found in 2020 by radial velocity.
HD 158259 f — 2.4 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 12 days; found in 2020 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.