Discovery of 'Phoenix' Exoplanet Challenges Planetary Evolution Theories

The Neptune-sized planet retains a puffy atmosphere despite intense radiation from its red giant star, prompting scientists to rethink late-stage planetary evolution.

Astronomers found 'Phoenix,' a hot Neptune exoplanet, using TESS and Keck Observatory telescopes.
Phoenix has a less dense, puffy atmosphere, defying expectations of atmospheric loss due to its proximity to a red giant star.
The exoplanet is 6.2 times larger than Earth and orbits its star every 4.2 days, about six times closer than Mercury is to the Sun.
Scientists estimate Phoenix's atmosphere is 60 times less dense than the densest known hot Neptune, and it will spiral into its star in about 100 million years.
The discovery may alter predictions about the future evolution of Earth's atmosphere when the Sun becomes a red giant.