The peculiarities of the big equatorial jet stream of Saturn’s atmosphere revealed

A study shows how are the structure and the temporal variations of the biggest jet stream of the Solar System.

The research, carried out by the Group of Planetary Sciences of the University of País Vasco, has used the PlanetCam camera installed at the Calar Alto Observatory 2.2m Telescope.

The atmosphere of Saturn has the wider and more intense jet stream of all the planets in the Solar System, with winds up to 1.650 km/h, thirteen times the value of the Earth’s hurricane winds, and with an extension of 70.000 km, more than five times our planet’s size. A study lead by University of País Vasco (UPV/EHU) using data from Calar Alto Observatory 2.2m telescope, has just revealed the peculiarities of this jet stream, which nature and energy are still unknown.

In June of last year, we discovered the presence of a bright spot on Saturn’s equator, moving at a speed of 1.600 km/h, something not observed since 1980”, points Agustín Sánchez Lavega, researcher of the Group of Planetary Sciences of UPV/EHV who leads the job.

Studying the movement of the clouds that formed the bright spot (a huge storm of about 7.000 km), and those present in surroundings, the researchers have been able to note the characteristics of the big equatorial jet stream and to establish the heights that the different atmospheric structures reach.

Besides, the team has determined that the winds get stronger with the deep: they have speeds of 1.100 km/h at the high atmosphere, but reach up to 1.650 km/h at about 150 km depth. Also, while the deep wind is stable, at the high atmosphere the speed of the equatorial jet stream is highly changing, as well as its wide. This could be caused by Saturn’s seasonal cycle of insolation, and by the changing shadow of the Saturn’s rings over the equator.


For this study they have been used observations obtained with small telescopes in several countries, with the Hubble Space Telescope and with PlanetCam camera, developed by the UPV/EHV team and installed at the Calar Alto Observatory 2.2m telescope. “The 2.2m telescope has become in recent years into an excellent and essential test laboratory for other institutions that can exploit their technological developments in the observatory allowing to get exciting results as these ones about Saturn”, Jesús Aceituno, the Calar Alto Observatory Director, says.

Saturn's complex atmosphere

The atmosphere of Saturn, a gaseous giant ten times bigger than the Earth, composed mainly with hydrogen, has also another important meteorological phenomenon above the planet’s equator that could play a role over the winds. It is the Semy-yearly Oscillation (SAO), which takes place about 50 km above the cloud ceiling, and that produces oscillation in the temperatures, together with a wind direction and intensity change from East to West.

In addition to Saturn’s equatorial meteorology complexity, at those latitudes is where the so named Big White Spot, a huge storm that surrounds the whole planet, has developed for three times, in 1876, 1933 and 1990. The study of the Group of Planetary Sciences points this huge storm is another changing agent on the equatorial jet stream.

All these phenomena, at a different scale, happen someway in our own planet. In this way, studying them in other worlds, and with very different conditions, allow us to move further in its understanding and modeling.

The German-Spanish Calar Alto Observatory is located at Sierra de los Filabres, north of Almería (Andalucía, Spain). It is jointly operated by the Instituto Max Planck de Astronomía in Heidelberg, Germany, and the Instituto de Astrofísica de Andalucía (CSIC) in Granada, Spain. Calar Alto has three telescopes with apertures of 1.23m, 2.2m and 3.5m. A 1.5m aperture telescope, also located at the mountain, is operated under control of the Observatorio de Madrid. 


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