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 2022, by transit (NASA Exoplanet Archive).
Its planets
HD 28109 c — 4.1 times Earth's width, Neptune-sized; its year lasts 56 days; about 370 °C, hotter than boiling water; found in 2022 by transit.
HD 28109 d — 3.1 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 84 days; about 290 °C, hotter than boiling water; found in 2022 by transit.
HD 28109 b — 2.7 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 23 days; about 590 °C, hotter than boiling water; found in 2022 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.