Mega-Earth GJ 523b is 23 times as massive as our planet—but only 2.5 times as wide

Astronomers have discovered a newly-identified planet named GJ 523b, which is incredibly dense and massive compared to Earth. Weighing in at 23 times the mass of our planet and spanning 2.5 times its size, researchers from the Wisconsin Center for Origins Research (WiCOR) have dubbed it a "Mega-Earth."

This planet, estimated to be 170 million years old, was discovered using a ground-based telescope in Arizona. It was identified as a potential candidate by the Transiting Exoplanet Survey Satellite (TESS), a NASA mission that monitors stars for dips in brightness, which could indicate a planet passing in front of the star.

Using data from the James Webb Space Telescope, WiCOR's team was able to determine the planet's density and atmospheric composition. Though it is not a Hycean exoplanet, it is mostly composed of dense rock with a massive core. This discovery is unusual as dense planets like this are typically small and rocky, not large like GJ 523b.

The unique nature of GJ 523b has led to several theories about its formation. It's possible that the planet lost much of its atmosphere due to close encounters with its star or that it began as two planets that collided and lost atmosphere in the process.

Despite being just one example, researchers hope that as more planets are identified, patterns will emerge that could help explain how such heavy and oversized planets form. With the upcoming launch of the Nancy Grace Roman Telescope, astronomers anticipate finding even more potential new planets, paving the way for further discoveries.