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Powerful Stratospheric Winds Measured on Jupiter for the First Time

Using the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, a team of astronomers have directly measured winds in Jupiter’s middle atmosphere for the first time.

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By analysing the aftermath of a comet collision from the 1990s, the researchers have revealed incredibly powerful winds, with speeds of up to 1450 kilometres an hour, near Jupiter’s poles. They could represent what the team have described as a “unique meteorological beast in our Solar System”.

Jupiter is famous for its distinctive red and white bands: swirling clouds of moving gas that astronomers traditionally use to track winds in Jupiter’s lower atmosphere. Astronomers have also seen, near Jupiter's poles, the vivid glows known as aurorae, which appear to be associated with strong winds in the planet’s upper atmosphere. But until now, researchers had never been able to directly measure wind patterns in between these two atmospheric layers, in the stratosphere.

Measuring wind speeds in Jupiter’s stratosphere using cloud-tracking techniques is impossible because of the absence of clouds in this part of the atmosphere. However, astronomers were provided with an alternative measuring aid in the form of comet Shoemaker–Levy 9, which collided with the gas giant in spectacular fashion in 1994. This impact produced new molecules in Jupiter’s stratosphere, where they have been moving with the winds ever since.

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