Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.
Facts
Kepler-539 c has an equilibrium temperature between −50 and +50 °C.
How it was found
First planet found in 2016, by transit and transit timing variations (NASA Exoplanet Archive).
Its planets
Kepler-539 b — 8.4 times Earth's width, Neptune-sized; its year lasts 130 days; about 120 °C, hotter than boiling water; found in 2016 by transit.
Kepler-539 c — 13 times Earth's width (estimated from its mass, not measured), a giant, Jupiter-sized or more; its year lasts about 3 Earth years; about −20 °C, below freezing; found in 2016 by transit timing variations.
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.