Proxima Centauri b (or Proxima b) is the closest known exoplanet to our solar system, located just 4.2 light-years away. It orbits Proxima Centauri, a red dwarf star and our sun’s nearest neighbor.
Key Physical Characteristics
- Planet Type: Rocky/Terrestrial world.
- Mass: Approximately 1.07 to 1.17 times the mass of Earth.
- Orbit: It is extremely close to its star—only 5% of the distance between Earth and the sun—completing a full orbit every 11.2 Earth days.
- Appearance: To an observer on the planet, its star would look about three times larger than the sun does to us on Earth.
Habitability & Environment
Proxima b is widely studied because it sits in its star’s habitable zone, the region where temperatures could theoretically allow for liquid water on the surface.
- Temperature: Its equilibrium temperature is estimated at -39 °C, but a stable atmosphere could potentially warm it to a range comfortable for life.
- Tidal Locking: It is likely tidally locked, meaning one side always faces the star (permanent day) while the other remains in constant darkness.
- Radiation Challenges: The planet is bombarded by X-ray and ultraviolet flares hundreds of times more intense than those Earth receives, which may strip away its atmosphere or make surface life difficult.
Current Research & Future Missions
As a prime target in the search for extraterrestrial life, it is featured prominently in Lisa Kaltenegger’s 2026 study of 45 top candidates for life-finding missions.
- Biofluorescence: Kaltenegger has proposed that life there might evolve to glow (biofluoresce) as a defense mechanism against intense UV radiation, which could be detectable from Earth.
- Atmospheric Analysis: Scientists are focused on using large telescopes to search for atmospheric markers like carbon dioxide and ozone.
- Interstellar Exploration: It is the primary target for future concepts like the Breakthrough Starshot initiative, which aims to send tiny probes to the system.
