Barnard’s Star planets revealed to be unusual and rocky

Astronomers have obtained detailed observations of four unusual, rocky planets orbiting Barnard’s Star, a red dwarf located less than six light-years from Earth. These planets are smaller than Earth and Venus but larger than Mars, representing a size category not found in our own solar system.

Researchers from the University of Cambridge analyzed the star’s chemical composition to infer the planets' makeup. The star shows high levels of magnesium, suggesting the planets are likely rich in this element. This high magnesium content may lead to the formation of periclase, a mineral that is less effective at storing water than the olivine found on Earth.

Due to their extreme proximity to the star—with the outermost planet orbiting ten times closer than Mercury orbits the Sun—these worlds likely lack significant atmospheres. Scientists believe stellar radiation and particles may have stripped away any original atmospheres within two billion years.