Cosmic Scale
TRAPPIST-1
Red dwarf · 40 light-years
How big is TRAPPIST-1?
TRAPPIST-1 is about 165,900 km across.
See TRAPPIST-1 in 3D, at true scale
TRAPPIST-1 is a cool red dwarf barely larger than Jupiter, and it has seven Earth-sized planets — the largest family of rocky worlds known around one star. Three of them orbit where liquid water could be possible.
At a glance
| Diameter | 165,900 km |
|---|---|
| Mass | 1.79 × 10²⁹ kg |
| Diameter compared with Earth | 13.0 × Earth |
| Distance | 40 light-years |
| Surface | 2,566 K |
| Planets | Seven, all Earth-sized |
| Found | 2016–2017 |
Good to know
- All seven orbits would fit comfortably inside Mercury's; the innermost planet's year lasts 1.5 days.
- From one planet's sky the others would appear larger than our Moon.
- Red dwarfs burn so slowly that this star will still be shining in trillions of years.
- Next smaller: Jupiter · 139,800 km
- Next larger: Proxima Centauri · 214,600 km