Gliese 12

The transiting exoplanet Gliese 12 b was discovered by TESS, and two independent studies confirming it as a planet were published in May 2024. Gliese 12 b is similar in size to Earth and Venus, and completes an orbit around its star every 12.8 days. Initially its mass was poorly constrained but was determined to be less than 4 times that of Earth. Measurements gathered in 2025 studies provided mass measurements of 0.71 and 0.95 Earth masses (M🜨). The latter also measured a planetary radius of 0.934 R🜨, and found a density of 7.0+2.3−2.1 g/cm, higher than the densities of the Solar System's terrestrial planets. This suggests a likely rocky composition, similar to Venus. While this, the former study used the discovery paper's radius (0.958 R🜨) and found a lower density that give less constraints on its composition.