GJ 667 Cf is the third potential habitable-zone planet in the remarkable triple-star system of Gliese 667, located 23.6 light-years away. It orbits the same red dwarf star (Component C) as its siblings, planets “c” and “e.”

Key Physical Characteristics

• Planet Type: Terrestrial (rocky) Super-Earth.
• Mass: It is approximately 2.7 times the mass of Earth (similar to planet “e”).
• Orbit: It completes one orbit around its star every 39 Earth days.
• The Star: It orbits the smallest star in a three-star system; the two larger stars would appear as incredibly bright, distant suns in the sky.

Habitability & Environment

In Lisa Kaltenegger’s research, GJ 667 Cf occupies the “sweet spot” between its warmer and colder siblings:

• Location: It is situated firmly within the Liquid Water Habitable Zone.
• Energy Intake: It receives about 60% of the starlight that Earth gets from the Sun. This puts it in a climate category similar to Mars, but because it orbits a red dwarf, its atmosphere might trap heat more efficiently.
• Temperature: With a modest greenhouse effect, this planet could be very temperate—potentially even more Earth-like in temperature than its closer sibling, planet “c,” which is much hotter.

Scientific Significance

• The “Crowded” Habitable Zone: GJ 667 Cf is part of a rare system where multiple planets (c, f, and e) all orbit within the same habitable zone. This allows scientists like Kaltenegger to study how life might “hop” between planets (a theory called lithopanspermia).
• Atmospheric Target: Because it sits in the middle of the habitable zone, it is a high-priority target for future telescopes to look for biosignatures like oxygen and methane.
• Stability: The triple-star gravity makes the orbits in this system complex, but GJ 667 Cf appears to have a stable enough path to have maintained a consistent climate for billions of years.

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Published @ March 24, 2026 9:18 am