The jet stream, a fast-moving band of air in Earth's upper atmosphere, blasts at speeds of more than 275 miles (442 kilometers) per hour, yet it is not the strongest in our solar system. The similar high-altitude winds on Neptune reach speeds of around 1,200 miles (2,000 kilometers) per hour. Those, however, pale in comparison to the jet-stream winds on WASP-127b.

Astronomers have detected winds roaring at nearly 20,500 miles (33,000 kilometers) per hour on this enormous gaseous planet, which is located in our Milky Way galaxy about 520 light-years from Earth in a tight orbit around a star comparable to our sun. A light-year is the distance light travels in one year, which is 5.9 trillion miles (9.5 trillion kilometers).

The supersonic jet-stream winds that round WASP-127b's equator are the fastest on any known planet.

"The planet contains an extraordinarily rapid circumplanetary jet wind. The wind velocity is surprisingly high," said main author Lisa Nortmann of the University of Göttingen in Germany, who published the study in the journal Astronomy & Astrophysics on Tuesday.

More than 5,800 planets beyond our solar system, known as exoplanets, have been identified. WASP-127b is a "hot Jupiter," a gas giant that orbits extremely close to its host star. WASP-127b has a diameter that is around 30% larger than Jupiter, our solar system's greatest planet. However, its mass is only around 16% that of Jupiter, making it one of the least dense - or puffiest - planets ever observed.

WASP-127b is a gas giant planet, which means it lacks a rocky or solid surface under its atmospheric layers. Instead, beneath the apparent atmosphere is gas that becomes denser and more pressured as one descends further into the planet," explained astrophysicist and research co-author David Cont of Ludwig Maximilian University of Munich in Germany.

It orbits its star every four days at a distance of about 5% of that between Earth and the sun, leaving it burned by stellar radiation. WASP-127b, like our moon, has one side that is always facing its star, known as the day side. The opposing side, known as the night side, always faces away. Its atmosphere is around 2,060 degrees Fahrenheit (1,400 degrees Kelvin/1,127 degrees Celsius), with the polar regions being less heated than the rest.

WASP-127b, like Jupiter, is primarily made of hydrogen and helium, but its atmosphere contains evidence of more complex compounds like as carbon monoxide and water, as discovered in this study.

The fact that a hot Jupiter's day side is intensely irradiated is thought to be a major factor in atmospheric dynamics.
"Answering the question of what drives these intense winds is challenging, as several factors influence wind patterns in exoplanet atmospheres," Cont told the audience.

"The primary source of energy for these winds is the intense irradiation from the host star," Cont said, adding that other factors also play a part in generating the wind patterns.

Higher atmospheric wind speeds have been recorded on two additional exoplanets, but only in winds from their day to night sides, not in winds that travel around the entire planet.

The researchers used CRIRES+, an instrument on the European Southern Observatory's Very Large Telescope in Chile, to track the speed of molecules in the planet's atmosphere. They used the "transit" approach to observe changes in the brightness of the host star as the planet passed in front of it, as seen from Earth.

Researchers can better comprehend the atmospheres of exoplanets thanks to advances in instrumentation, observational techniques, and data analysis.

"We are moving beyond inferring average features, such as global average temperature or chemical abundances, to investigating three-dimensional aspects of these atmospheres, such as wind patterns, temperature changes, and chemical processes across different longitudes and latitudes. These findings demonstrate how much remains to be uncovered and how each new observation surprises this fast changing profession," Cont added.