Trappist 1

Trappist-1 is a nearby red dwarf star best known for the discovery of a relatively large number of rocky planets orbiting it.^[1]

Trappist-1 was discovered in 1999 by a team of Astronomers lead by John Giziz, at approximately 40 lightyears from the Solar system.^[1]

In May 2016 Astronomers using the Transiting Planets and Planetesimals Small Telescope in Chile (TRAPPIST) announced it was circled by at least three exoplanets.^[1] It was the first exoplanet discovery by the telescope, hence the name "Trappist-1". By February 2017 Astronomers using other telescopes had detected four more exoplanet. At least several of these planets were believed to be within Trappist-1's habitable zone.

Exoplanets known to be orbiting Trappist-1 As of 2026^[update]^[2]
planet	distance	mass	period	habitability	notes
Trappist 1 b	0.01154 AU	1.374	1.5	unlikely	Determined to be too hot to be considered in that habitable zone.^[3]^[4]
Trappist 1 c	0.0158 AU	1.308	2.4	unlikely	Determined to be too hot to be considered in that habitable zone.^[3]
Trappist 1 d	0.02227 AU	0.388	4	unlikely As of August 2025^[update]	In August 2025 spectroscopic measurements performed the James Web Space Telescope determined that Trappist-1 d was unlikely to have an atmosphere^[5]
Trappist 1 e	0.02925 AU	0.692	6.1 days	possible As of September 2025^[update]	In September 2025 spectroscopic measurements performed the James Web Space Telescope ruled out that Trappist-1 e was like either Planet Mars or Planet Venus.^[6]^[7]
Trappist 1 f	0.03849 AU	1.039	9.25
Trappist 1 g	0.04683 AU	1.321	12.4
Trappist 1 h	0.06189 AU	0.326	18.8

References

↑ ^1.0 ^1.1 ^1.2 "10 Things: All About TRAPPIST-1". NASA Science. 2018-02-20. Retrieved 2026-07-07. The star we today call TRAPPIST-1 was first discovered in 1999 by astronomer John Gizis and colleagues. At that time, the ultra-cool dwarf star got the unwieldy name 2MASS J23062928-0502285, because it was spotted with the Two Micron All-Sky Survey (2MASS).
↑ "What is Webb Revealing About the TRAPPIST-1 System?". NASA Science. 2026-01-15. Archived from the original on 2026-05-12. Retrieved 2026-07-07.
↑ ^3.0 ^3.1 M.J. Way (2025-02-05). "TRAPPIST-1 d: Exo-Venus, Exo-Earth, or Exo-Dead?". The Astronomical Journal Letters. 980 (1). Retrieved 2026-07-07. TRAPPIST-1 d is generally assumed to be at the boundary between a Venus-like world and an Earth-like world, although recently published works on TRAPPIST-1 b and c raise concerns that TRAPPIST-1 d may be similarly devoid of a substantial atmosphere.
↑ Alicia Cermak (2017-10-02). "TRAPPIST-1 b". NASA Science. Archived from the original on 2026-06-27. Retrieved 2026-07-07. TRAPPIST-1 b is a super Earth exoplanet that orbits an M-type star. Its mass is 1.374 Earths, it takes 1.5 days to complete one orbit of its star, and is 0.01154 AU from its star. Its discovery was announced in 2016.
↑ "Webb Narrows Atmospheric Possibilities for Earth-sized Exoplanet TRAPPIST-1 d". NASA Science. 2025-08-13. Archived from the original on 2026-04-08. Retrieved 2026-07-07. The exoplanet TRAPPIST-1 d intrigues astronomers looking for possibly habitable worlds beyond our solar system because it is similar in size to Earth, rocky, and resides in an area around its star where liquid water on its surface is theoretically possible. But according to a new study using data from NASA’s James Webb Space Telescope, it does not have an Earth-like atmosphere.
↑ Alicia Cermak (2017-02-23). "TRAPPIST-1 e". NASA Science. Archived from the original on 2026-06-03. Retrieved 2026-07-07. TRAPPIST-1 e is a terrestrial exoplanet that orbits an M-type star. Its mass is 0.692 Earths, it takes 6.1 days to complete one orbit of its star, and is 0.02925 AU from its star. Its discovery was announced in 2017.
↑ Paige Colley (2025-09-08). "Study finds exoplanet TRAPPIST-1e is unlikely to have a Venus- or Mars-like atmosphere". MIT News. Retrieved 2026-07-07. In an open-access paper published today in The Astrophysical Journal Letters, astronomers used JWST to take a closer look at the atmosphere of the exoplanet TRAPPIST-1e, located in the TRAPPIST-1 system. While they haven’t found definitive proof of what it is made of — or if it even has an atmosphere — they were able to rule out several possibilities.

[NasaTrappist-1-2018-02-20-1] 1.0 ^1.1 ^1.2 "10 Things: All About TRAPPIST-1". NASA Science. 2018-02-20. Retrieved 2026-07-07. The star we today call TRAPPIST-1 was first discovered in 1999 by astronomer John Gizis and colleagues. At that time, the ultra-cool dwarf star got the unwieldy name 2MASS J23062928-0502285, because it was spotted with the Two Micron All-Sky Survey (2MASS).

[NasaTrappist2026-01-15-2] "What is Webb Revealing About the TRAPPIST-1 System?". NASA Science. 2026-01-15. Archived from the original on 2026-05-12. Retrieved 2026-07-07.

[AstronomicalJournalLetters2025-02-05-3] 3.0 ^3.1 M.J. Way (2025-02-05). "TRAPPIST-1 d: Exo-Venus, Exo-Earth, or Exo-Dead?". The Astronomical Journal Letters. 980 (1). Retrieved 2026-07-07. TRAPPIST-1 d is generally assumed to be at the boundary between a Venus-like world and an Earth-like world, although recently published works on TRAPPIST-1 b and c raise concerns that TRAPPIST-1 d may be similarly devoid of a substantial atmosphere.

[NasaTrappist-1-b-2017-10-02-4] Alicia Cermak (2017-10-02). "TRAPPIST-1 b". NASA Science. Archived from the original on 2026-06-27. Retrieved 2026-07-07. TRAPPIST-1 b is a super Earth exoplanet that orbits an M-type star. Its mass is 1.374 Earths, it takes 1.5 days to complete one orbit of its star, and is 0.01154 AU from its star. Its discovery was announced in 2016.

[NasaWebbTrappist-1-d-2025-08-13-5] "Webb Narrows Atmospheric Possibilities for Earth-sized Exoplanet TRAPPIST-1 d". NASA Science. 2025-08-13. Archived from the original on 2026-04-08. Retrieved 2026-07-07. The exoplanet TRAPPIST-1 d intrigues astronomers looking for possibly habitable worlds beyond our solar system because it is similar in size to Earth, rocky, and resides in an area around its star where liquid water on its surface is theoretically possible. But according to a new study using data from NASA’s James Webb Space Telescope, it does not have an Earth-like atmosphere.

[NasaTrappist-1-e-2017-02-23-6] Alicia Cermak (2017-02-23). "TRAPPIST-1 e". NASA Science. Archived from the original on 2026-06-03. Retrieved 2026-07-07. TRAPPIST-1 e is a terrestrial exoplanet that orbits an M-type star. Its mass is 0.692 Earths, it takes 6.1 days to complete one orbit of its star, and is 0.02925 AU from its star. Its discovery was announced in 2017.

[MitNews2025-09-08-7] Paige Colley (2025-09-08). "Study finds exoplanet TRAPPIST-1e is unlikely to have a Venus- or Mars-like atmosphere". MIT News. Retrieved 2026-07-07. In an open-access paper published today in The Astrophysical Journal Letters, astronomers used JWST to take a closer look at the atmosphere of the exoplanet TRAPPIST-1e, located in the TRAPPIST-1 system. While they haven’t found definitive proof of what it is made of — or if it even has an atmosphere — they were able to rule out several possibilities.

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