GJ 1002 c

GJ 1002 c is the outer companion to GJ 1002 b, located in the same star system just 15.8 light-years away. While its sibling “b” sits on the warmer inner edge, planet “c” is situated further out, making it a “colder” version of Earth.

Key Physical Characteristics

Planet Type: Terrestrial (rocky) world.
Mass: It is an Earth-mass planet, approximately 1.13 times the mass of Earth.
Orbit: It takes about 21.2 Earth days to complete one orbit around its red dwarf star.
Energy Intake: It receives significantly less starlight than Earth—only about 27% of the solar radiation we get from the Sun. This puts it near the “outer edge” of the habitable zone, similar to the position of Mars in our solar system.

Habitability & Environment

In Lisa Kaltenegger’s 2026 study, GJ 1002 c is a key target for studying the limits of habitability:

The Greenhouse Requirement: Because it receives less light, this planet would likely be a frozen ice ball unless it has a thick atmosphere with strong greenhouse gases (like CO2 or methane) to trap heat and maintain liquid water.
Stable Environment: Like its sibling, it benefits from orbiting a very quiet red dwarf. This lack of violent solar flares means any atmosphere it developed early on has a high chance of still being there today.
Potential “Ice World”: Depending on its volcanic activity and atmospheric density, it could range from a global “Snowball Earth” to a planet with a liquid ocean hidden under an ice shell.

Scientific Significance

The Perfect Comparison: Having two Earth-mass planets in the same system (b and c) at different distances allows Kaltenegger and her team to test how atmospheric evolution works. It’s like having two different experiments running under the same sun.
Future Imaging: Because the GJ 1002 system is so close to us, it is a primary candidate for direct imaging by the upcoming Extremely Large Telescopes (ELTs). This would allow us to actually “see” the light reflected off the planet’s surface.

Published @ March 24, 2026 9:13 am