Powerful winds detected raging in Jupiter’s stratosphere © ESO/L Calçada & NASA/JPL-Caltech/SwRI/MSSS/PA

Powerful winds detected raging in Jupiter’s stratosphere

Astronomers track debris stirred up by a comet that crashed into the planet in 1994 to make to the first measurement of winds in the mid-atmosphere.

Scientists have gathered further evidence of just how blustery it is on Jupiter, recording wind speeds of almost 1,450km/h raging in the gas giant’s atmosphere.

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The fifth planet from the Sun is renowned for having some seriously windy conditions in the upper and lower parts of its atmosphere, but less has been known about the middle part of the atmosphere, called the stratosphere.

It’s usually possible to get an idea of the wind speed on a planet by tracking the movement of clouds, but Jupiter’s stratosphere does not have any, despite them being abundant in other layers of the atmosphere.

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Now, astronomers at Atacama Large Millimeter/submillimeter Array (ALMA), in northern Chile, have found another way of measuring wind speed.

It’s all thanks to the comet Shoemaker-Levy 9, which collided with the gas giant in spectacular fashion in 1994.

The impact of this event sent new molecules – hydrogen cyanide – blowing around the gas giant, which the team at ALMA could then follow.

They detected the presence of strong jets, with speeds of up to 400 metres per second, the equivalent of 1,450km/h, located under Jupiter’s poles.

These staggeringly powerful blasts rage at more than twice the maximum speeds reached by storms in Jupiter’s famous Great Red Spot, and more than three times the wind speed measured in Earth’s strongest tornadoes.

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“Our detection indicates that these jets could behave like a giant vortex with a diameter of up to four times that of Earth, and some 900 kilometres in height,” said Bilal Benmahi, co-author of the research and PhD student at the University of Bordeaux.

Reader Q&A: How big would Jupiter be if it were stripped of all of its gases?

Asked by: Shannon Ripsher

Thanks to NASA’s Juno mission, we now have a few clues as to what Jupiter’s internal structure looks like. At its centre, extending out by up to 30 per cent of the planet’s radius, is a dense, liquid core made of ionised (‘metallic’) hydrogen and helium, mixed with dissolved heavier elements. The pressure and temperature inside Jupiter drop off as you get further from the centre. This means the liquid interior eventually gives way to a gaseous atmosphere (also mostly hydrogen and helium).

The depth of this liquid/gas boundary is not well defined, but Jupiter is probably fully liquid a few thousand kilometres below the planet’s cloud tops. So, even if we stripped Jupiter of its gases, it would still be bigger than Saturn.

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