TRAPPIST-1 g
Planet· orbits the Sun
TRAPPIST-1 g — the largest of the seven (1.13 Earth radii) and the outer habitable-zone planet, receiving about a quarter of Earth's sunlight on a 12-day orbit. Likely rocky with a substantial water or ice fraction. Potentially habitable only with a strong warming atmosphere; never imaged.
Open in 3D viewSee TRAPPIST-1 g in the live, interactive 3D map
Key facts
Mass
7.89 × 10²⁴ kg
1.32 M⊕
Radius
7,193 km
1.13× wider than Earth
Surface gravity
10.2 m/s²
1.04× Earth's
Year
12.35 Earth days
Distance from TRAPPIST-1
7,005,668 km
Science
Physical
- Mass
- 7.89 × 10²⁴ kg · 1.32 M⊕
- Radius
- 7,193 km · 1.13× wider than Earth
- Density
- 5,061 kg/m³ · 5.1× water
- Surface gravity
- 10.2 m/s² · 1.04× Earth's
- Escape velocity
- 12.1 km/s · 1.08× Earth's
Orbital
- Semi-major axis
- 7,005,668 km
- Eccentricity
- 0.00208
- Inclination
- 0.00 °
- Orbital period
- 12.4 days
- Perihelion
- 6,991,096 km
- Aphelion
- 7,020,240 km
- Mean orbital velocity
- 41.2 km/s
Atmosphere
- Composition
- Unknown — none confirmed. At the outer edge of the habitable zone it receives only about a quarter of Earth's sunlight, so liquid water would require a strong greenhouse atmosphere that has not been found.
Composition
- Bulk composition
- Likely rocky with a substantial water or ice fraction (radius 1.13 Earth — the largest of the seven). Never imaged.
- Surface appearance
- Appearance based on NASA/JPL-Caltech's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The surface shown is an artistic representation, shown only in Vision mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 0.252 S⊕ · 25% of the sunlight Earth receives
- Equilibrium temperature
- 197 K (-76 °C)
Discovery & history
- Discovered
- February 22, 2017
- By
- Michaël Gillon et al. (TRAPPIST / Spitzer)
- Method
- Transit detection
- Name
- Designated 'g' by its position in the system — planets are lettered inward to outward starting at 'b', so TRAPPIST-1 b is the innermost and h the outermost.
Revealed in February 2017, when a 20-day campaign by NASA's Spitzer Space Telescope with ground-based telescopes showed TRAPPIST-1 hosts seven transiting planets (Gillon et al., Nature, 2017). Its mass was later measured from the tiny timing tugs the planets exert on one another (transit-timing variations).
Images
Images from open archives · credit shown per image