Winds circling a gas giant more than 500 light years from Earth have been detected flowing at supersonic speeds approaching 33,000 kilometers (20,000 miles) per hour, making them the fastest air currents on any known planet by a wide margin.
Researchers from Europe cleaned and analyzed the spectrum of light reflected from the planet WASP-127b, uncovering two contrasting peaks in water and carbon dioxide signals suggestive of supersonic flows disturbing the planet’s cloud tops.
“Part of the atmosphere of this planet is moving towards us at a high velocity while another part is moving away from us at the same speed,” says the study’s lead author Lisa Nortmann, an astrophysicist at the University of Göttingen in Germany.
“This signal shows us that there is a very fast, supersonic, jet wind around the planet’s equator.”
Fast is an understatement. At an incredible 7.5 to 7.9 kilometers per second, they outstrip any hurricane or jetstream known to science.
Here on Earth, the fastest puff of wind on record was a blustery 407 kilometers (253 miles) per hour, measured on Australia’s Barrow Island in 1996. Neptune has the highest wind speeds in our Solar System, but even its 1,770 kilometer-per-hour high-altitude currents feel more like a mild breeze by comparison.
WASP-127b is a wispy puffball of a world, slightly larger than Jupiter yet with just 16 percent of Jupiter’s mass.
It’s also believed to be tidally locked, rotating in step with every 4.2-Earth-day lap around its star, so one side is perpetually baked to temperatures exceeding 1,000 degrees Celsius (1832 degrees Fahrenheit), and the other never turns from the cold night sky.
Discovered in 2016, the world has been the focus of intense investigation, resulting in some of the most precise measurements of an exoplanet’s atmosphere to date.
Nortmann and her team used an instrument called a cryogenic high-resolution infrared echelle spectrograph on the European Space Agency’s Very Large Telescope located in Chile’s Atacama Desert to measure the composition of WASP-127b’s gases.
A closer inspection of the signals revealed two clear peaks – one indicating the material was approaching the observers quickly, the other moving away just as fast.
Variations in the strength of the signals between the planet’s poles may indicate extreme temperature variations of potentially hundreds of degrees Celsius between dusk and dawn, making WASP-127b a world of hellish extremes and yet not entirely unfamiliar.
“This shows that the planet has complex weather patterns just like Earth and other planets of our own system,” says author Fei Yan, an astronomer with the University of Science and Technology of China.
Cast adrift in this flow, a space tourist would circle the giant planet in hours, basking in the radiation of a Sun-like star that fills its sky.
In addition to the surprise discovery of WASP-127b’s incredible winds, the team detected expected levels of carbon monoxide where none had been seen before, canceling any need for exotic theories of planetary formation.
This hot cotton ball is far from alone as far as low-density planets go, representing a strange category of gas giants that could contribute to our knowledge of how planetary systems emerge from their swirling nebulae.
Having a clear measure of the air currents churning up material on extreme worlds such as this can inform models describing how planets form, grow, and evolve, potentially helping us better understand the history and fate of planets within our own Solar System.
This research was published in Astronomy & Astrophysics.
