NASA's newest planet discovery is unlike anything seen before

Key Points:

• Astronomers have discovered a new exoplanet named GJ 523b, classified as a "mega-Earth" due to its extraordinary mass and rocky composition, challenging existing planet formation theories.
• GJ 523b has about 23 times the mass of Earth, a radius 2.5 times larger than Earth, and an exceptionally high density of approximately 7.8 grams per cubic centimeter, indicating it is predominantly rocky rather than gaseous.
• The planet orbits its star every 17.75 days and is relatively young at around 170 million years old, making its massive, dense, and mostly rocky nature unexpected by current scientific models.
• Traditional models suggest planets exceeding 20 Earth masses should accumulate thick gaseous atmospheres and become gas giants, but GJ 523b either lost its atmosphere due to stellar heat or formed from a collision of two massive rocky protoplanets stripping away lighter gases.
• This discovery provides new insights into planetary formation and suggests that the universe hosts more diverse and complex planetary types than previously understood.