Astronomers Discover Rocky 'Mega-Earth' GJ 523b That Defies Planet Formation Theories

Key facts

• Astronomers discovered a rocky exoplanet named GJ 523b, informally dubbed a 'mega-Earth'.
• GJ 523b has a mass 23 times that of Earth and a radius about 2.55 times larger.
• The planet's density is approximately 126.82 grams per cubic inch.
• The exoplanet orbits its host star every 17.75 days, and the system is about 170 million years old.
• The discovery was made using NASA's Transiting Exoplanet Survey Satellite (TESS) and confirmed with the WIYN 3.5-meter Telescope at Kitt Peak National Observatory.
• The planet's existence challenges traditional planetary formation models, which predict such massive rocky bodies should become gas giants.
• Two proposed theories for its formation are atmospheric stripping and a giant impact between protoplanets.
• The research paper detailing the discovery has been submitted to The Astronomical Journal.