IMAGEAt 23.5 times Earth’s mass, GJ 523b is massive enough that standard planet-formation models struggle to explain why it didn’t accumulate a huge hydrogen-helium envelope — yet the planet is extraordinarily dense and apparently mostly rock, and astrono...At 23.5 times Earth’s mass, GJ 523b is massive enough that standard planet-formation models struggle to explain why it didn’t accumulate a huge hydrogen-helium envelope — yet the planet is extraordinarily dense and apparently mostly rock, and astronomer Space Daily
