30 Mayo 2017 17:28
The Juno spacecraft shows Jupiter’s poles for the first time, and reveals a magnificent inferno full of unexplainable phenomena
Things are getting strange in Jupiter. Just when we thought we knew almost everything we needed to know about this gas giant, the first data gathered by the Juno spacecraft show us that this isn’t the case: almost all the hypotheses we - or rather, the world’s top astronomers - have reached regarding the fifth planet from the sun seem to have been off-target.
‘Discoveries about its core, composition, magnetosphere, and poles are as stunning as the photographs the mission is generating,’ asserted mission leader Scott Bolton, in this press statement.
These discoveries are the result of Juno’s first two flights in August 2016. The spacecraft descended to within 4000 kilometres of Jupiter’s cloud tops - none of the previous missions had ventured so close fearing the planet’s intense radiation would damage the craft’s instruments -, entering a highly elliptical orbit which allowed it to come close to both poles. The data gathered has since been examined in two studies (which can be found here and here) recently published in a special edition of Science. And both uncover some surprising findings.
'NASA scientists have found “a complex, gigantic and turbulent world” which is very different to what was expected.'
For example, the mission team wanted to know more about the ‘bright, oval-shaped masses’ that gather around Jupiter’s two poles. Scientists were expecting to find a massive storm with a distinctive vortex dominating the atmosphere at each pole, as occurs on Saturn, but no: the data and images captured by Juno show endless gigantic cyclones, densely clustered and swirling about the polar regions. Some of these cyclones reach up to 1400 kilometres in diameter and rise to over 100 kilometres in height.
Nobody expected that. The observations are nothing like anything else before seen in the Solar System.
Surprises were also in store when they ‘looked’ below the cloud tops. The temperature data for the lower atmospheric layers suggests plumes of ammonia emanating from the deep equatorial zones, like geysers, and soaring beyond the cloud layer.
‘It resembles a deeper, wider version of the air currents that rise from Earth’s equator and generate the trade winds,’ Bolton explains.
The scientists leading the mission also highlight the existence of a colossal cloud measuring some 7,000 kilometres in diameter situated way above the rest of the north pole. Nobody can explain how it could have reached so high.
'The data and images captured by Juno show endless gigantic cyclones, densely clustered and swirling about the polar regions'
Things got even stranger in the second study, when Juno was sent to explore Jupiter’s magnetic field. Although investigators already reckoned on finding a powerful magnetic field, what they discovered was twice as powerful as models had predicted.
The data sent by Juno revealed an immense magnetic field measuring around 7.766 guas, more than ten times bigger than the Earth’s. This field is also more dynamic than expected, with an uneven distribution.
When scientists looked closer at Jupiter’s magnetosphere - the region around the planet where the magnetic field deflects a large part of the solar wind - they stumbled upon several additional surprises.
Firstly, the analysis of the spacecraft’s encounters with so-called bow shocks, as it orbited the planet, suggests that Jupiter’s magnetosphere was expanding at the time of Juno’s approach.
Then, there is the matter of the luminous auroras, detected by Juno as it made its way towards the poles.
'The data sent by Juno revealed an immense magnetic field measuring around 7.766 guas, more than ten times bigger than the Earth’s'
The Earth’s northern lights are produced when a stream of electrically charged solar particles collides with the magnetosphere. Scientists were expecting something similar with Jupiter, but the spacecraft’s measuring instruments reveal an inverse reality: the Jovian Auroras seem to be brought about by charged particles emanating from the planet’s polar regions and smashing through its magnetosphere. In other words, these particles, rather than falling onto the planet, are welling up from it.
In sum, NASA scientists have discovered ‘a complex, gigantic and turbulent world’ which is very different to what was expected. This all means that it’s time to ‘rethink’ Jupiter, because what we thought we knew… is no longer of any use.
Now, it’s a question of waiting and seeing, as there are bound to be more surprises in store.
‘On our next flyby on July 11, we will fly directly over one of the most iconic features in the entire solar system: Jupiter’s Great Red Spot,’ announced Bolton. ‘If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments.’