TRAPPIST-1 f is the fifth planet in the TRAPPIST-1 system, located 40 light-years away. While its sibling “e” is seen as an Earth-twin, planet “f” is a colder, potentially exotic world.

Key Physical Characteristics

• Planet Type: Terrestrial (rocky) world.
• Mass: Approximately 68% to 100% of Earth’s mass.
• Orbit: It completes one orbit every 9.2 Earth days.
• Size: Its radius is roughly 1.04 times that of Earth, meaning it is slightly larger but less dense than our home planet.

Habitability & Environment

In Lisa Kaltenegger’s research, TRAPPIST-1 f represents a “cool Earth” or a “warm Mars”:

• Energy Intake: It receives about 38% of the starlight that Earth gets. This puts it in the outer region of the habitable zone.
• Composition: Because it is less dense than Earth despite its similar size, scientists believe it contains a significant amount of volatile materials—likely a deep layer of water-ice surrounding a rocky core.
• Atmosphere: To have liquid water, it would need a thick atmosphere rich in greenhouse gases like CO2 or methane to trap enough heat from its dim red sun.

Scientific Significance

• The “Eyeball” Potential: Like the other planets in the system, it is tidally locked. If it has an atmosphere, it might look like an eyeball world: a massive ice shell covering most of the planet, with a small, liquid ocean directly under the sun.
• Observational Target: Because it is larger than planet “e,” it is an easier target for telescopes to search for methane or water vapor in its atmosphere.
• Life Potential: Kaltenegger notes that if life exists here, it would have to thrive in a much dimmer, redder environment than on Earth, potentially under a protective layer of ice.

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Published @ March 24, 2026 9:23 am