JUNOCAM a camera for the public
JunoCam has made it possible for amateur astronomers to take their own photos of Jupiter
Of all Juno’s eight science instruments, the one that has undoubtedly captured the public’s imagination like no other is JunoCam.
This visible-light camera, with a 58° field of view, was intended to facilitate unprecedented educational outreach and NASA has invited ‘citizen scientists’ to select regions to photograph during each perijove passage. Telescope observations by ground-based astronomers and an ability to plot atmospheric features directly onto the mission’s website have enabled Jupiter to be imaged by members of the public at resolutions as fine as 2.9km per pixel.
Described as “the public’s camera” and “science in a fishbowl”, JunoCam has produced stunningly surreal imagery of the Solar System’s largest planet. Colourenhanced views have presented Jupiter in vivid blues, reds, creams and browns and tracked swirling, contorting storms, spots and eddies, whilst artists and graphic designers have also been inspired to apply their craft to the bewildering perspectives.
Mik Petter used mathematical formulae to digitally re-imagine the Great Red Spot as something akin to a petri dish, overcrowded with colourised microorganisms, whilst David Englund created a composition of which French impressionist Monet would have been proud. Others have introduced an element of fun. One view, captured in May 2017, was dubbed ‘Jovey McJupiterFace’ by citizen scientist Jason Major, on account of its spooky similarity to a human face, complete with two raging storms in place of eyeballs.
and with their spiral arms frequently touching, they retain distinct, individual morphologies. At high northern latitudes, Juno also measured the Little Red Spot – the planet’s third-biggest anticyclone – at half the size of Earth, whilst at 40° south it revealed the ‘string of pearls’, a chain of oval-shaped, counterclockwise-revolving storms.
Juno has sampled thermal microwave radiation from the atmosphere, revealing the equatorial belts penetrate deep inside the planet. So too do atmospheric winds, which endure far longer than similar processes on Earth. Contrastingly, higherlatitude belts and zones evolve into other structures, indicating variable ammonia concentrations. Water, although identified by earlier missions, remains surprisingly elusive. In October 2017, clouds of ammonia ice and possibly water were found. By measuring the oxygen-hydrogen ratio and water balance, theories on how Jupiter formed can be confidently addressed.
Gravity’s regional variations
Gravitational observations, published in March 2018, indicate striking north-south asymmetries, not dissimilar to that seen in the belts and zones. This arises from gaseous flows deep within the planet and Juno showed that the visible eastward and westward jet streams also exhibit north-south asymmetry. The magnitude of this asymmetry allows the jets’ depth to be determined. Remarkably,
“Microwave radiometry revealed that the Great Red Spot’s roots plunge up to 100 times deeper than our oceans”
Jupiter’s 3,000km-deep weather layer comprises one per cent of the planet’s entire mass, compared to 0.000001 per cent in the case of Earth. And in one of the greatest surprises of the mission, this gaseous world rotates almost as a rigid body beneath its massive weather layer.
In July 2017, the spacecraft hurtled 9,000km over the famous Great Red Spot. This centuries-old storm has morphed in shape and diminished in size over time, today measuring 16,350km across – 1.3 times larger than Earth – and Juno detected a tangle of dark, veiny clouds weaving through it. Microwave radiometry revealed that its roots plunge to a depth of 300km, which is some 50-100 times deeper than our oceans.
For now, the future for this mission remains uncertain beyond July 2018, as Juno awaits its fate. Yet in two years it has revolutionised humanity’s understanding of a world 1,300 times bigger than our own. “We knew that Jupiter would throw us some curves,” says Bolton. “We didn’t expect that we would have to take a step back and begin to rethink this as a whole new Jupiter.”