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 1997, by radial velocity (NASA Exoplanet Archive).
Its planets
rho CrB c — 5.7 times Earth's width (estimated from its mass, not measured), Neptune-sized; its year lasts 100 days; about 180 °C, hotter than boiling water; found in 2016 by radial velocity.
rho CrB b — 14 times Earth's width (estimated from its mass, not measured), a giant, Jupiter-sized or more; its year lasts 40 days; about 340 °C, hotter than boiling water; found in 1997 by radial velocity.
rho CrB e — 1.8 times Earth's width (estimated from its mass, not measured), a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 13 days; about 730 °C, hotter than boiling water; found in 2023 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.