Star system, 21 light-years
Gliese 581 and its three planets
GJ 581 e is an exoplanet about 1.38 times Earth's width (a size estimated from its mass), 21 light-years away, orbiting closer to its star than the habitable zone we compute for it.
Gliese 581 is a star of spectral type M3.0 V, 21 light-years from us, with three 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
GJ 581 e
GJ 581 e is an exoplanet about 1.38 times Earth's width (a size estimated from its mass), 21 light-years away, orbiting closer to its star than the habitable zone we compute for it.
- Width
- 1.38 × Earth's estimated
- Mass
- 2.48 times Earth's measured
- One year
- 3.1481 days measured
- Distance from its star
- 0.02799 AU from the Archive
- Temperature of a bare ball there
- 507 K computed, not measured
- Starlight, against Earth's
- 15.8 × 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 2009. Its orbit is closer to its star than the habitable zone computed for it.
See GJ 581 e in 3D · The picture is an artist's impression.
GJ 581 b
GJ 581 b is an exoplanet about 4.79 times Earth's width (a size estimated from its mass), 21 light-years away, orbiting closer to its star than the habitable zone we compute for it.
- Width
- 4.79 × Earth's estimated
- Mass
- 20.5 times Earth's measured
- One year
- 5.3686 days measured
- Distance from its star
- 0.0399 AU from the Archive
- Temperature of a bare ball there
- 425 K computed, not measured
- Starlight, against Earth's
- 7.76 × 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 2005. Its orbit is closer to its star than the habitable zone computed for it.
See GJ 581 b in 3D · The picture is an artist's impression.
GJ 581 c
GJ 581 c is an exoplanet about 2.5 times Earth's width (a size estimated from its mass), 21 light-years away, orbiting closer to its star than the habitable zone we compute for it.
- Width
- 2.5 × Earth's estimated
- Mass
- 6.81 times Earth's measured
- One year
- 12.9211 days measured
- Distance from its star
- 0.0718 AU from the Archive
- Temperature of a bare ball there
- 317 K computed, not measured
- Starlight, against Earth's
- 2.4 × 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 2007. Its orbit is closer to its star than the habitable zone computed for it.
See GJ 581 c in 3D · The picture is an artist's impression.
The star
- Surface temperature
- 3,500 K
- Width
- 0.302 × the Sun's
- Mass
- 0.295 × the Sun's
- Spectral type
- M3.0 V
- Distance
- 21 light-years
- Habitable zone, computed
- 0.1152 to 0.2237 AU from the star