Free Astronomy Magazine March-April 2026

MARCH-APRIL 2026 T his artist’s concept shows what the ultra-hot super-Earth exoplanet TOI-561 b could look like based on observations from NASA’s James Webb Space Telescope and other observatories. Webb data suggests that the planet is surrounded by a thick atmosphere above a global magma ocean. TOI-561 b is the innermost of four planets orbiting TOI-561, a 10-billion-year-old G-type star located roughly 280 light-years from Earth, in the constellation Sextans. [NASA, ESA, CSA, Ralf Crawford (STScI)] The magma ocean could circulate some heat, but without an atmos- phere, the nightside would probably be solid, limiting flow away from the dayside. A thin layer of rock vapor on the surface of the magma ocean is also possible, but on its own would likely have a much smaller cooling effect than observed. “We really need a thick volatile-rich atmosphere to explain all the observations,” said Anjali Piette, coauthor from the Uni- versity of Birmingham, United King- dom. “Strong winds would cool the dayside by transporting heat over to the nightside. Gases like water vapor would absorb some wavelengths of near-infrared light emitted by the surface before they make it all the way up through the atmosphere. (The planet would look colder be- cause the telescope detects less light.) It’s also possible that there are bright silicate clouds that cool the at- mosphere by reflecting starlight.” While the Webb observations pro- vide compelling evidence for such an atmosphere, the question remains: How can a small planet exposed to such intense radiation can hold on to