The Case of the Helium-Shrouded Exoplanet With the Hydrogen Comet-like Tail

An artist’s concept of the vast envelope of atomic hydrogen that envelopes the nearby helium-dominated exoplanet Gliese 436b. The radiation pressure from the planet’s host star causes the gradual escape over time of significant amounts of hydrogen from Gliese 436b’s atmosphere into space, which subsequently forms a large comet-like tail that follows the planet [...]