13point8100 ly map
7 known planets · 40.5 light years

TRAPPIST-1

TRAPPIST-1 is a red dwarf (M8.0 V) 40.5 light years away, with 7 confirmed planets, 2 of them in the habitable zone. Distances and orbital speeds are to scale; the star and planets are enlarged so you can see them.

Day 0
habitable zone (estimate)planet orbits

Green band: where liquid water could exist on a planet's surface. Drag to turn the system, pinch or scroll to zoom.

The star

The star

TRAPPIST-1

Type
M8.0 V
Surface
≈ 2,566 K
Size
0.12 × the Sun
Mass
0.09 × the Sun
Brightness
0.000553 × the Sun
Habitable zone
0.0223–0.0393 AU
Facts and sources →Facts and sources →

The planets

TRAPPIST-1

TRAPPIST-1 b

Year
1.51 days
Distance from star
0.0115 AU
Mass
1.4 Earths
Size
1.1 × Earth
Temperature
≈ 398 K (+124 °C)
Found
2016, transit (La Silla Observatory)
Outside the habitable zone
TRAPPIST-1

TRAPPIST-1 c

Year
2.42 days
Distance from star
0.0158 AU
Mass
1.3 Earths
Size
1.1 × Earth
Temperature
≈ 340 K (+67 °C)
Found
2016, transit (La Silla Observatory)
Outside the habitable zone
TRAPPIST-1

TRAPPIST-1 d

Year
4.05 days
Distance from star
0.0223 AU
Mass
0.39 Earths
Size
0.79 × Earth
Temperature
≈ 286 K (+13 °C)
Found
2016, transit (La Silla Observatory)
Near the edge of the habitable zone
TRAPPIST-1

TRAPPIST-1 e

Year
6.10 days
Distance from star
0.0293 AU
Mass
0.69 Earths
Size
0.92 × Earth
Temperature
≈ 250 K (-23 °C)
Found
2017, transit (Multiple Observatories)
In the habitable zone
TRAPPIST-1

TRAPPIST-1 f

Year
9.21 days
Distance from star
0.0385 AU
Mass
1 Earths
Size
1 × Earth
Temperature
≈ 218 K (-55 °C)
Found
2017, transit (Multiple Observatories)
In the habitable zone
TRAPPIST-1

TRAPPIST-1 g

Year
12.35 days
Distance from star
0.0468 AU
Mass
1.3 Earths
Size
1.1 × Earth
Temperature
≈ 197 K (-76 °C)
Found
2017, transit (Multiple Observatories)
Outside the habitable zone
TRAPPIST-1

TRAPPIST-1 h

Year
18.77 days
Distance from star
0.0619 AU
Mass
0.33 Earths
Size
0.76 × Earth
Temperature
≈ 172 K (-101 °C)
Found
2017, transit (Multiple Observatories)
Outside the habitable zone

Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.

How we know

The shadow

The planet passes in front of its star and dims it by a fraction of a percent, every orbit. The dip gives the planet's size and year.

Sources

  1. Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 31 Oct 2026. 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.
  2. Position: HYG Database v4.1 (CC BY-SA 4.0).
  3. Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.
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