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TRAPPIST-1e - exoplanet orbiting the habitable zone with atmosphere

Posted on:May 12, 2023

Artist’s conception of TRAPPIST-1e

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TRAPPIST-1e is one of the seven planets in the TRAPPIST-1 system and is the fourth planet in order from the star. It has a mass similar to Earth and receives about the same amount of starlight as Earth does from the Sun.


Planet typeTerrestrial
Discovery date22 February 2017
Discovered bySpitzer Space Telescope
Mass0.692 Earths
Planet radius0.92 x Earth
Orbital radius0.02925 AU
Orbital period6.1 days
Detection methodTransit


TRAPPIST-1e was detected with the transit method, where the planet blocked a small percentage of its host star’s light when passing between it and Earth. The discovery of TRAPPIST-1e and the other planets in the TRAPPIST-1 system was significant because it represented the largest number of Earth-sized planets found around a single star and the first time that multiple potentially habitable planets had been found around a single star.

Host star

The planet orbits ultracool M-type dwarf star named TRAPPIST-1. TRAPPIST-1 have the potential to remain stable for up to 12 trillion years, which is over 1,000 times longer than the Sun and because of this ability it is likely TRAPPIST-1 will be one of the last remaining stars in the Universe.

The star has a mass of 0.089 Solar mass and a radius of 0.121 Solar radius. It has a temperature of 2516 K and is anywhere between 3 and 8 billion years old. The star is metal-rich and its luminosity is 0.0522% of that of the Sun.


Artist’s conception of TRAPPIST-1e and TRAPPIST-1 host star


TRAPPIST-1e is considered one of the most promising potentially habitable exoplanets known.

One key factor that affects habitability is the planet’s atmosphere. It is confirmed that TRAPPIST-1e has a compact, hydrogen-free atmosphere like those of our Solar System’s rocky planets, further raising the chances of habitability.

Another factor is the planet’s surface conditions. TRAPPIST-1e is thought to be a rocky planet like Earth, but its surface conditions may be vastly different due to its close proximity to its star.

The planet is tidally locked which means one side of its hemisphere permanently facing towards the star.


TRAPPIST-1e will be an early target of the James Webb Space Telescope in a research program which will help to better analyze the planet’s atmosphere and search for the chemical signs of life or biosignatures.


TRAPPIST-1 system has been considered an excellent candidate by astronomers for exoplanet research since the very beginning.

TRAPPIST-1e represents the holy grail for planet-hunting astronomers, as it orbits in the star’s habitable zone and could host oceans of surface water.