Voyager 1 at the speed it moved outward over the year to 2026-10-25 (JPL Horizons). Driving: nonstop, never refuelling.
Facts
55 Cnc f has an equilibrium temperature between −50 and +50 °C.
How it was found
First planet found in 1996, by radial velocity (NASA Exoplanet Archive).
Its planets
55 Cnc b — 14 times Earth's width (estimated from its mass, not measured), a giant, Jupiter-sized or more; its year lasts 15 days; about 430 °C, hotter than boiling water; found in 1996 by radial velocity.
55 Cnc c — 8.5 times Earth's width (estimated from its mass, not measured), Neptune-sized; its year lasts 44 days; about 230 °C, hotter than boiling water; found in 2004 by radial velocity.
55 Cnc d — 13 times Earth's width (estimated from its mass, not measured), a giant, Jupiter-sized or more; its year lasts about 13 Earth years; about −170 °C, below freezing; found in 2002 by radial velocity.
55 Cnc e — 1.9 times Earth's width, a 'sub-Neptune' — bigger than Earth, smaller than Neptune; its year lasts 18 hours; about 1,700 °C, hot enough to melt rock; found in 2004 by radial velocity.
55 Cnc f — 7.6 times Earth's width (estimated from its mass, not measured), Neptune-sized; its year lasts 260 days; about 4 °C, between freezing and boiling; found in 2007 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.