Overview
Proxima Centauri b, discovered August 2016, is an Earth-sized exoplanet orbiting our Sun’s nearest neighbor—Proxima Centauri, just 4.24 light-years away. Located in the habitable zone, it’s the closest potentially life-supporting world, making it prime target for future interstellar missions.
Discovery
European Southern Observatory’s team used HARPS spectrograph (La Silla Observatory, Chile) to detect wobble in Proxima Centauri caused by orbiting planet’s gravity. Radial velocity method measured star’s motion—16-year campaign finally confirmed planet 2016. Planet has minimum mass 1.27 Earths, orbits every 11.2 days at 0.05 AU (7.5 million km—closer than Mercury to our Sun).
Habitable Zone Location
Proxima Centauri is red dwarf (M-class star)—12% Sun’s mass, 15% diameter, surface temperature 5,400°F (vs. Sun’s 10,000°F). Emits mostly infrared light; habitable zone much closer than Sun’s. Proxima b receives similar energy as Earth despite proximity. Tidal locking likely (one side always faces star)—permanent day/twilight/night zones. Atmosphere could redistribute heat, or planet might be too irradiated.
Challenges for Life
Red dwarf flares release intense radiation—Proxima Centauri flares regularly, increasing brightness 68% (2018 superflare). Planets this close bombarded by X-rays, UV radiation, stellar wind—atmosphere could be stripped away (like Mars). Magnetic field and thick atmosphere might protect surface. Age (4.85 billion years, similar to Sun) means billions of years for life to arise—if conditions permit.
Breakthrough Starshot
Proxima b’s proximity inspired Breakthrough Starshot project (announced April 2016): laser-propelled nanocraft traveling 20% light speed, reaching system in 20 years (vs. 6,300 years with current tech). Stephen Hawking endorsed initiative. $100 million initial funding; full mission estimated $5-10 billion. Concept: gram-scale probes with light-sails accelerated by Earth-based laser array. Decades away from feasibility, but Proxima b makes interstellar exploration conceivable.
Follow-Up Observations
2019: Possible second planet (Proxima c) detected farther out, but less certain. 2020: Third planet candidate (Proxima d) announced, 26% Earth mass, 5-day orbit—too close for habitability. JWST observations attempted detecting Proxima b’s atmosphere; stellar activity complicates analysis. No biosignature detection yet—but search continues.
Sources: ESO press release Aug 2016, Nature discovery paper (Anglada-Escudé et al.), JWST observation proposals, Breakthrough Starshot documentation