# Discovery of exoplanet GJ 523b > Live situation record from CLSTR: https://clstr.news/situations/discovery-of-exoplanet-gj-523b > Updated: 2026-08-23T15:02:49.000Z. Sources: 13. Developments: 2. Astronomers have identified a unique exoplanet, GJ 523b, located approximately 87 light-years away. Data from NASA’s TESS mission and the WIYN Telescope indicate the planet, informally called a ‘Mega-Earth’, has a mass roughly 23.5 times that of Earth but a radius only 2.55 times larger. This high density suggests a predominantly rocky composition. The discovery challenges existing planetary formation models because a planet of this mass would typically accumulate a thick hydrogen and helium atmosphere to become a gas giant. However, GJ 523b lacks such an atmosphere despite the system being relatively young, at approximately 170 million years old. Researchers are investigating whether high stellar radiation stripped the atmosphere or if a massive collision between protoplanets occurred. Further observations reveal that GJ 523b follows an unusual orbital path, passing near the host star's poles rather than orbiting on the equatorial plane. Scientists suggest this extreme inclination may be caused by the gravitational influence of an undiscovered sibling planet within the system. ## Timeline ### 2026-08-23: Exoplanet GJ 523b discovered with unusual mass and orbit Astronomers discovered GJ 523b, a massive exoplanet with 23 times Earth's mass but a small radius, featuring an unusual polar orbit and a lack of a thick atmosphere. 3 sources. https://clstr.news/cluster/exoplanet-gj-523b-discovered-with-unusual-mass-and-orbit ### 2026-08-20: GJ 523b discovery challenges planetary formation theories Astronomers have discovered GJ 523b, a dense ‘Mega-Earth’ with 23.5 times Earth's mass, challenging theories on how massive rocky planets form without becoming gas giants. 10 sources. https://clstr.news/cluster/astronomers-reveal-new-details-on-exoplanets-gj-504b-and-gj-523b --- Cite as: Discovery of exoplanet GJ 523b. CLSTR, https://clstr.news/situations/discovery-of-exoplanet-gj-523b