Star system, 4.2 light-years
Proxima Centauri and its two planets
Proxima Cen b is an exoplanet about 1.02 times Earth's width (a size estimated from its mass), 4.2 light-years away, orbiting in its star's computed habitable zone.
Proxima Centauri is a star of spectral type M5.5 V, 4.2 light-years from us, with two known planets. This page takes them one at a time.
Drawn at the system's own scale, every orbit from the Archive's numbers.
What is measured, what is computed, what is imagined.
measured The period, and where the table says so the width and the mass, by the method named in each section.
computed Anything marked computed: the size of an orbit where Kepler's third law corrects the table, the temperature of a bare ball at that distance, the starlight received, and the habitable zone.
imagined The picture is an artist's impression. Nobody has seen the surface of a planet of another star: its colour, clouds and land are not known, and the share picture says so in its corner.
The planets
Proxima Cen d
Proxima Cen d is an exoplanet about 0.692 times Earth's width (a size estimated from its mass), 4.2 light-years away, orbiting closer to its star than the habitable zone we compute for it.
- Width
- 0.692 × Earth's estimated
- Mass
- at least 0.26 times Earth's measured
- One year
- 5.12338 days measured
- Distance from its star
- 0.02881 au from the Archive
- Temperature of a bare ball there
- 296 K computed, not measured
- Starlight, against Earth's
- 1.82 × computed
It was found by the back-and-forth wobble its pull puts into its star's motion, seen as a shift in the colour of the star's light in 2025. Its orbit is closer to its star than the habitable zone computed for it.
See Proxima Cen d in 3D · The picture is an artist's impression.
Proxima Cen b
Proxima Cen b is an exoplanet about 1.02 times Earth's width (a size estimated from its mass), 4.2 light-years away, orbiting in its star's computed habitable zone.
- Width
- 1.02 × Earth's estimated
- Mass
- at least 1.055 times Earth's measured
- One year
- 11.1846 days measured
- Distance from its star
- 0.04848 au from the Archive
- Temperature of a bare ball there
- 228 K computed, not measured
- Starlight, against Earth's
- 0.642 × computed
It was found by the back-and-forth wobble its pull puts into its star's motion, seen as a shift in the colour of the star's light in 2016. Its orbit lies inside the conservative habitable zone computed for its star (liquid water on a rocky world's surface would be possible there, which says nothing about whether any is).
See Proxima Cen b in 3D · The picture is an artist's impression.
The star
- Surface temperature
- 2,900 K
- Width
- 0.141 × the Sun's
- Mass
- 0.1221 × the Sun's
- Spectral type
- M5.5 V
- Distance
- 4.2 light-years
- Habitable zone, computed
- 0.04051 to 0.08096 au from the star
- Stars in the system
- 3