Radio map shows Jupiter’s stormy weather has deep roots
In a study published in the Journal Science, new technique showed swirling ammonia beneath Jupiter’s cloud tops mirrors those on surface according to Australian and American astronomers. Jupiter’s Great Red Spot and other stormy surface features extend 30 to 100 kilometres below the enigmatic surface of the gas giant, a new radio map of the planet’s atmosphere has revealed.Also showed hotspots are ammonia-poor regions encircling planet.The new findings to help understanding ahead of July 4 arrival of NASA’s Juno spacecraft.Jupiter is the fifth planet from the Sun and is the largest planet in the solar system with a diameter of 142,984 kilometres.Jupiter takes 11.86 earth years to orbit the Sun and has an average of 778 million kilometres distance from the Sun.A day in Jupiter lasts 10 hours and is orbited by at least 67 moons.This latest findings are the clearest glimpse yet of what lies beneath Jupiter’s cloud tops has shown patterns of swirling ammonia mirroring those seen on the surface. That suggests stormy weather captured by Voyager’s 1979 encounter with the planet has deep roots.The team, led by astronomer Imke de Pater from the University of California, Berkeley, was able to pull off this wonderful feat by observing the wavelengths of radio waves coming through the atmosphere over a period of time.The red spot is at least 100 kilometres thick,” radio astronomer Professor Robert Sault who together with his colleagues made their discovery using a newly upgraded radio telescope in New Mexico called the Karl G Jansky Very Large Array.They zeroed in on ammonia, which the 1995 Galileo probe found was present in larger-than-expected amounts on Jupiter.Radio waves emitted by the planet are absorbed by ammonia so, knowing this, the astronomers were able to calculate the amount of ammonia in different parts of the atmosphere, down to 100 kilometres below the surface clouds.This gave them a picture of the distribution and circulation of ammonia in the atmosphere.
The development of a technique to adjust for the planet’s rotation was central to the success of the project.Radio maps take hours to produce, but Jupiter spins rapidly once every 10 hours.This meant, in previous attempts to peer below the surface clouds, ammonia that was moving upwards was getting confused with that which was moving downwards.”We in essence created a three-dimensional picture of ammonia gas in Jupiter’s atmosphere, which reveals upward and downward motions within the turbulent atmosphere,” de Pater said.These maps clearly show hot spots, areas that appear brighter through the telescope where ammonia levels are more active, which suggests that these areas may play a role in creating the cloud formations that are commonly seen on the planet’s outer atmosphere.”With radio, we can peer through the clouds and see that those hotspots are interleaved with plumes of ammonia rising from deep in the planet, tracing the vertical undulations of an equatorial wave system,” said team member Michael Wong from UC Berkeley.”Previous radio images were smeared so we’ve developed a technique that prevents that smearing from happening,” Professor Sault said.The radio maps showed ammonia-poor air sinking into the planet, similar to how dry air descends from above the cloud layers on Earth.The map also showed hotspots so-called because they appear bright in radio and thermal infrared images are ammonia-poor regions that encircle the planet like a belt just north of the equator.Between these hotspots are ammonia-rich upwellings, bringing ammonia from deeper in the planet.The July 4 arrival of NASA’s Juno spacecraft will focus on detecting water on the gas planet, a substance Galileo surprisingly found little evidence of when it plunged through the Jovian atmosphere. Jupiter is the next biggest player in the solar system after the Sun, so understanding it is key to understanding the evolution of the solar system, Professor Sault said.