ultra-cool dwarf star

TRAPPIST-1 (or 2MASS J23062928-0502285) is an ultracool red dwarf star located almost 40 light years away from the Sun in the constellation of Aquarius. The red dwarf is known for having seven Earth-sized rocky planets around it.[1] These planets were discovered between 2016 and 2017, and are likely rocky and some may even have liquid water on them.[2] Four of these planets (d, e, f, and g) are in the habitable zone, so they are most likely to have liquid water. Three other planets here (b, c, and h) are not in the habitable zone, and are likely not habitable.

Artists Kepler of the image of TRAPPIST-1.



In August of 2017, the Hubble Space Telescope possibly found traces of possible water in the atmospheres of some of the TRAPPIST-1 planets.[3][4]

Impression of the planets around TRAPPIST-1.
  • Trappist 1-b - The closest planet to Trappist 1 and likely akin to Venus. It's extremely hot (over 1400°K/ 1224°C at the surface) due to the planet only being 1.7 million km from its star. The planet has a likely runaway greenhouse effect that immures almost all of the heat that hits it.
  • Trappist 1-c - The next closest planet to Trappist 1 and also likely Venus like.

  • Trappist 1-d - At the innermost edge of the system's habitable zone, Trappist 1-d could be livable or too hot like Venus, it is debatable.
  • Trappist 1-e - Squarely in the habitable zone, this planet is likely to have a slightly higher land to ocean ratio than Earth.
  • Trappist 1-f - This planet is probably a water world.
  • Trappist 1-g - The furthest planet from Trappist 1 that is confirmed to be in the system's liveable zone and could be a water world with little dry land.
  • Trappist 1-h - The furthest out and the smallest planet in the system. The gravity is similar to that of the Moon and it's likely to be covered in an ice shell.


  1. | TRAPPIST-1 Worlds Are Rocky and Rich in Water, New Research Uncovers | September 05, 2018
  2. | New Clues to TRAPPIST-1 Planet Compositions, Atmospheres | Feb. 5, 2018 | NASA
  3. | Hubble delivers first hints of possible water content of TRAPPIST-1 planets | 31 August, 2017
  4. "First evidence of water found on TRAPPIST-1 planets". 4 September 2017.