A rocky planet called TOI-561 b completes an entire year in under 11 hours and orbits so close to its star that its surface is thought to contain a vast magma ocean. Its star is roughly 10 billion years old — twice the age of the Sun — yet after billions of years of extreme radiation, James Webb found compelling evidence that the planet still has a thick atmosphere.

A rocky planet called TOI-561 b completes an entire year in under 11 hours and orbits so close to its star that its surface is thought to contain a vast magma ocean. Its star is roughly 10 billion years old — twice the age of the Sun — yet after billions of years of extreme radiation, James Webb found compelling evidence that the planet still has a thick atmosphere.

On TOI-561 b, a year is shorter than a working day. The planet circles its star in about 10 hours and 34 minutes, racing around at roughly one-fortieth of Mercury’s distance from the Sun. It is probably tidally locked, keeping one hemisphere under permanent daylight. That should make the dayside brutally simple: exposed rock heated until it melts, with little more than a thin veil of mineral vapour above it. Instead, the James Webb Space Telesco…