Free Astronomy Magazine March-April 2025

15 MARCH-APRIL 2025 ASTRO PUBLISHING planet rotates. “This is something we haven’t seen before,” says Nort- mann. It is the fastest wind ever measured in a jetstream that goes around a planet. In comparison, the fastest wind ever measured in the Solar System was found on Nep- tune, moving at ‘only’ 0.5 km per second (1800 km/h). The team, whose research was pub- lished in Astronomy & Astrophysics , mapped the weather and make-up of WASP-127b using the CRIRES+ instrument on ESO’s VLT. By measuring how the light of the host star travels through the planet’s upper atmosphere, they managed to trace its composition. Their results confirm the presence of water vapour and carbon monoxide molecules in the planet’s atmosphere. But when the team tracked the speed of this material in the atmosphere, they ob- served — much to their sur- prise — a double peak, indicating that one side of the atmosphere is moving towards us and the other away from us at high speed. The researchers conclude that powerful jetstream winds around the equator would ex- plain this unexpected result. Further building up their weather map, the team also found that the poles are cooler than the rest of the planet. There is also a slight temperature difference between the morning and evening sides of WASP-127b. “This shows that the planet has complex weather pat- terns just like Earth and other plan- ets of our own System,” adds Fei Yan, a co-author of the study and a professor at the University of Sci- ence and Technology of China. The field of exoplanet research is rapidly advancing. Up until a few years ago, astronomers could meas- T his artist’s visualisation of WASP-127b, a giant gas planet located about 520 light- years from Earth, shows its newly discovered supersonic jet winds that move around the planet’s equator. With a speed of 9 km per second (33,000 km/h), this is the fastest jetstream of its kind ever measured in the Universe. [ESO/L. Calçada]