NASA's Juno spacecraft has executed the first of 36 orbital flybys on August 27, 2016, when it came about 4 200 km (2 500 miles) above Jupiter's swirling clouds. It was Juno's first flyby with instruments switch on and it sent back first-ever images of Jupiter's north pole. What Juno saw was storm systems and weather activity unlike anything previously seen on any of our solar system's gas-giant planets.
"First glimpse of Jupiter's north pole, and it looks like nothing we have seen or imagined before," said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. "It's bluer in color up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to - this image is hardly recognizable as Jupiter. We're seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features."
Video courtesy NASA/JPL
One of the most notable findings of these first-ever pictures of Jupiter's north and south poles is something that the JunoCam imager did not see.
"Saturn has a hexagon at the north pole," said Bolton. "There is nothing on Jupiter that anywhere near resembles that. The largest planet in our solar system is truly unique. We have 36 more flybys to study just how unique it really is."
Along with JunoCam snapping pictures during the flyby, all eight of Juno's science instruments were energized and collecting data. The Jovian Infrared Auroral Mapper (JI-RAM), supplied by the Italian Space Agency, acquired some remarkable images of Jupiter at its north and south polar regions in infrared wavelengths.
"JIRAM is getting under Jupiter's skin, giving us our first infrared close-ups of the planet," said Alberto Adriani, JIRAM co-investigator from Istituto di Astrofisica e Planetologia Spaziali, Rome.
"These first infrared views of Jupiter's north and south poles are revealing warm and hot spots that have never been seen before. And while we knew that the first ever infrared views of Jupiter's south pole could reveal the planet's southern aurora, we were amazed to see it for the first time. No other instruments, both from Earth or space, have been able to see the southern aurora. Now, with JIRAM, we see that it appears to be very bright and well structured. The high level of detail in the images will tell us more about the aurora's morphology and dynamics."
Video courtesy NASA/JPL
Among the more unique data sets collected by Juno during its first scientific sweep by Jupiter was that acquired by the mission's Radio/Plasma Wave Experiment (Waves), which recorded ghostly- sounding transmissions emanating from above the planet. These radio emissions from Jupiter have been known about since the 1950s but had never been analyzed from such a close vantage point.
"Jupiter is talking to us in a way only gas-giant worlds can. Waves detected the signature emissions of the energetic particles that generate the massive auroras which encircle Jupiter's north pole. These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them," said Bill Kurth, co-investigator for the Waves instrument from the University of Iowa, Iowa City.
The download of six megabytes of data collected during the six-hour transit, from above Jupiter's north pole to below its south pole, took one-and-a-half days. While analysis of this first data collection is ongoing, some unique discoveries have already made themselves visible.
NASA's Juno spacecraft captured this view as it closed in on Jupiter's north pole, about two hours before closest approach on August 27, 2016. Image credit: NASA/JPL-Caltech/SwRI/MSSS
Juno was about 78 000 km (48 000 miles) above Jupiter's polar cloud tops when it captured this view on August 27, showing storms and weather unlike anywhere else in the solar system. Two versions of the image have been contrast-enhanced differently to bring out detail near the dark terminator and near the bright limb. Image credit: NASA/JPL-Caltech/SwRI/MSSS
The JunoCam instrument acquired this view of Jupiter's south polar region about an hour after closest approach on August 27, 2016, when the spacecraft was about 94 599 km (58 700 miles) above the cloud tops. Image credit: NASA/JPL-Caltech/SwRI/MSSS
This infrared image from Juno provides an unprecedented view of Jupiter's southern aurora. Such views are not possible from Earth. Image credit: NASA/JPL-Caltech/SwRI/MSSS
This montage of 10 JunoCam images shows Jupiter growing and shrinking in apparent size before and after NASA's Juno spacecraft made its close approach on August 27, 2016. Image credit: NASA/JPL-Caltech/SwRI/MSSS
This southern hemisphere view of Jupiter shows the transition between banded structures near the equator and the more chaotic features near the polar region. Image credit: NASA/JPL-Caltech/SwRI/MSSS
Featured image credit: NASA/JPL-Caltech/SwRI/MSSS