A planet called WASP-127b, about 520 light-years from Earth, has a jet stream flowing around its equator at speeds of up to 33,000 kilometers per hour, 18 times faster than Neptune’s winds, the fastest found anywhere in our solar system.

Astronomers have measured the movement of the atmosphere around the equator of the planet WASP-127b at a speed of approximately 9 kilometers per second, or about 33,000 kilometers per hour. This giant exoplanet is located about 520 light-years away, but its weather left a subtle enough velocity signature to separate gas moving toward Earth from gas moving away.

The result, obtained using the European Southern Observatory’s Very Large Telescope in Chile, is the fastest jet stream motion of its kind ever measured on a planet. The European Southern Observatory compared it to winds of 1,800 kilometers per hour on the planet Neptune, which holds the wind record in the solar system. By this criterion, WASP-127b’s maximum speed at the equator is more than 18 times greater.

No telescope has photographed the clouds rushing around the distant world, and no probe has carried an anemometer into its atmosphere. The measurement came from Doppler shifts in the spectral signatures of water vapor and carbon monoxide during a single transit. A model then linked these transitions to a rapidly rotating equatorial jet.

There’s also a highlight hidden within the 33,000km/h heading. The peer-reviewed paper calculates a wind speed of 7.7 plus or minus 0.2 kilometers per second after subtracting the planet’s expected rotation. The upper figure describes the maximum movement of the atmosphere at the equator when flow and circulation are combined.

WASP-127b is large, light, and close to its star

WASP-127b was announced in 2016 and belongs to the family of extremely hot giant planets often called hot Jupiters. the NASA Exoplanet Archive It places its star at a distance of about 159.5 parsecs, equivalent to approximately 520 light-years. The planet completes its orbit every 4,178 days at a distance close to 0.05 astronomical units.

It is slightly wider than Jupiter, but carries only a small fraction of Jupiter’s mass. Values ​​accepted in the archives give a radius of about 1.31 times the radius of Jupiter, a mass of approximately 0.165 Jupiter’s masses and an average density of about 0.097 grams per cubic centimeter. This makes WASP-127b an exceptionally puffy world with an extended atmosphere.

The high altitude in the atmosphere is useful to astronomers. When a planet passes in front of its star, some of the starlight filters through the gas surrounding its edge before it reaches Earth. Atoms and molecules filter narrow bands of wavelengths from this light. Their motion also shifts those features toward shorter or longer wavelengths through the Doppler effect.

Two molecular peaks revealed opposite motions

Use the team CRIRES+, high-resolution infrared spectrometer Mounted on one of the 8.2 meter Very Large Telescope units. The observations covered the transit in the infrared K range, where researchers searched the changing spectrum for expected patterns of different atmospheric molecules.

Water vapor and carbon monoxide were detected. Instead of producing one broad velocity peak, each molecule generated two different peaks. Part of the atmosphere was approaching observers at a high speed while another part was retreating at a similar speed.

This is the expected signature when the fast equatorial flow crosses the edges of the visible planet during the transit. One end carries the partially absorbed gas toward Earth and the opposite end carries it away. the Peer-reviewed analysis in Astronomy and astrophysics Use a 2D retrieval model to infer an eastward SST and weaker contributions from the poles.

Geometry is more useful than a simple estimate of wind speed. The two peaks correspond to the ends of morning and evening, which are the boundaries between the two hemispheres of permanent day and night. The polar signal is muted, which could mean the poles are much cooler or that high clouds are blocking molecular signatures there. The evidence also tentatively favors the end-morning temperature to be about 175 K cooler than the end-evening temperature, although the uncertainty is large enough that the temperature difference is not a firm finding.

How does a speed of 7.7 km/s become 33,000 km/h?

Researchers expect WASP-127b to be tidally locked, meaning one orbit takes the same 4,178 days as a single orbit. This prediction was not confirmed by direct rotation measurement. Using the planet’s estimated radius and orbital period, we obtain an equatorial rotation speed of about 1.6 kilometers per second.

The atmospheric retrieval found the total equatorial velocity to be close to 9.3 kilometers per second. After removing the expected spin, the team calculated the speed of the plane itself at 7.7 plus or minus 0.2 kilometers per second, which equates to about 27,700 kilometers per hour.

The ESO announcement rounded the maximum motion to 9 kilometers per secondThat is, approximately 33 thousand kilometers per hour, and this is described as the speed reached by jet winds. This is the source of the widely reported number. It captures the maximum rate at which atmospheric material moves around the equator, while the paper’s value of 7.7 kilometers per second isolates the flow relative to the supposed rotating planet.

Neither number is read directly from a single moving line. The researchers removed features of Earth’s atmosphere and the star’s contribution, correlated the remaining spectra with molecular templates, and fed the coupled signals to an atmospheric model. It is the unusually clean separation between the two peaks that makes the inference strong.

The “18 times Neptune” comparison uses a speed of 1800 km/h

The European Southern Observatory set a value of 33,000 kilometers per hour along with Neptune’s wind speed of 0.5 kilometers per second, or 1,800 kilometers per hour. Dividing one by the other we get about 18.3, which supports the “more than 18 times” comparison in the title.

Planetary wind figures are often rounded, and different official summaries use slightly different values. NASA describes Neptune’s winds Exceeding 2000 kilometers per hour. Using 2000 as the denominator yields a ratio of about 16.5. The comparison therefore depends on the rounded Neptune standard chosen.

The physical conclusion remains unchanged. Neptune has the fastest winds ever measured in the solar system, and the inferred equatorial motion of WASP-127b is much faster. Comparing the spectrum of distant exoplanets with clouds tracked by Voyager also involves different methods, so the multiple is best understood as a scale rather than a laboratory precision.

The planet is not spatially resolved

The artist’s illustration could show a globe wrapped in a bright equatorial band, but observations have not resolved WASP-127b into surface or cloud features. The planet and star remain essentially point sources. The researchers separated regions of the atmosphere with different velocities, not by seeing those regions as pixels.

This limitation is also an achievement. The high-resolution spectrum encoded enough information to distinguish between the two extremes and conclude that the two poles contribute less force. Account of the University of Göttingen He asserts that the result provides a new test for models of global rotation of exoplanets. It also confirms the presence of water vapor and carbon monoxide in an atmosphere where previous studies on the carbon monoxide signal differed.

The word “supersonic” needs a similar context. The relevant speed of sound depends on the composition of the local atmosphere and temperature. It’s no comparison to sound traveling through room temperature air on Earth. The study’s classification indicates the speed of sound expected in the hot, hydrogen-rich atmosphere of the planet WASP-127b.

From record to method for space weather mapping

Space Daily Initial report on WASP-127b winds It covered the record when the result came out in January 2025. The deeper significance is what the observation demonstrates: that the geography of the atmosphere can be retrieved from a planet too distant to be imaged as a disk.

Ground tools currently have an advantage for this work because they can provide the much needed fine speed accuracy. ESO expects that the Very Large Telescope and the planned ANDES spectrometer will be able to resolve more precise patterns and extend the scope of the method toward smaller planets.

WASP-127b is an unusually suitable target, as it has a wide atmosphere and a very short orbit. Rocky worlds will be much harder. However, the double peaks show a path from molecular detection to circulation reconstruction. The speed record is astonishing, but the ability to separate morning and evening, the equator and the poles of an unresolved exoplanet is the most permanent result.