Barnard b is a sub-Earth-mass exoplanet orbiting Barnard’s Star, the nearest single star to our Sun at just 6 light-years away. Detected using the European Southern Observatory’s Very Large Telescope and instruments like ESPRESSO over five years of observations, it has a mass of about 0.3 Earth masses and completes an orbit every 3.2 days at a distance of 0.023 AU—20 times closer than Mercury is to our Sun. Despite the cool red dwarf host, the planet’s proximity results in scorching surface temperatures of around 125°C, ruling out habitability. This discovery highlights the challenges of finding low-mass worlds and revives interest in Barnard’s Star, previously thought planetless after a 2018 candidate was debunked. Three other potential planets in the system await confirmation.
