After nearly a year in orbit, the Juno spacecraft is starting to crack some of Jupiter’s many mysteries.
This week, the journals Science and Geophysical Research Letters published the first batch of scientific findings about Jupiter, based on Juno’s trips there. Discoveries include enormous new cyclones swirling around the planet’s poles, a magnetic field that’s much more variable than expected, and some evidence that Jupiter’s core is not as dense and compact as once thought. “What we’ve learned so far is Earth-shattering. Or should I say, Jupiter-shattering,” Scott Bolton, Juno’s principal investigator, said, in a press statement, making his very best dad joke.
The science is great and fascinating. But let’s be honest: We’re here for the pictures. And Juno is delivering unprecedented beautiful portraits of the largest planet in our solar system. The images released along with the scientific papers are arresting — one part van Gogh painting, one part Pillars of Creation. Add to that the awesome size of what’s in them: Even seemingly small details on Jupiter can be larger than the entire Earth.
As Juno orbits around Jupiter’s poles once every 53 days, it gets within a few thousand miles of the planet’s cloud tops. On these approaches, Juno’s cameras reveal details, disturbances, sinewy undulations, massive storms, and ammonia clouds that spread out in iridescent folds like an oil film on a sidewalk puddle.
In the above photo, Juno — 5,500 miles above Jupiter — is looking at waves of clouds made out of ammonia and ice. You can make out details as small as 4 miles across, NASA reports. (The space agency notes that the colors in these photos have been enhanced a bit to bring out more details in the atmosphere.) You can make out different atmospheric “fronts” that make up the weather patterns on Jupiter.
Here’s another crop of that same photo.
And now let’s zoom out a few tens of thousands of miles.
Next is an extremely cool sequence of images. It’s essentially a stop-motion time-lapse series of Juno’s view as it gets closer and closer to Jupiter in its orbit. NASA explains:
The first image on the left shows the entire half-lit globe of Jupiter, with the north pole approximately in the center. As the spacecraft gets closer to Jupiter, the horizon moves in and the range of visible latitudes shrinks. The third and fourth images in this sequence show the north polar region rotating away from our view while a band of wavy clouds at northern mid-latitudes comes into view. By the fifth image of the sequence the band of turbulent clouds is nicely centered in the image. The seventh and eighth images were taken just before the spacecraft was at its closest point to Jupiter, near Jupiter's equator.
You can see the details better in this vertical crop.
And here’s Juno looking out toward space. The light band in the middle is Jupiter’s wispy ring.
Okay, these photos are great. But why did we send a probe to Jupiter?
Even though Jupiter is the largest planet in the solar system, scientists know remarkably little about it.
Basic questions about the planet they’d like to answer include:
- Does Jupiter have a solid core?
- How does it generate such extreme levels of radiation?
- How did Jupiter form and evolve?
Juno is equipped with nine scientific instruments, including sensors that can measure gravity, probe deep into Jupiter’s atmosphere, and test the planet’s magnetic fields, as well as various cameras to capture the planet across a range of the electromagnetic spectrum.
Jupiter is made up of the same basic ingredients as the sun — mainly hydrogen and helium. Scientists are hoping a close-up investigation of its surface can reveal some history of the origin of our solar system. What’s more, the galaxy may be littered with other gas giants we haven’t yet discovered.
There’s a reason NASA has never sent a probe to fly so close to the surface of Jupiter: The planet has a magnetic field that can fry electronics to a cinder.
Just like Earth has a protective bubble of radiation (a magnetosphere, which is what creates the aurora borealis light shows around the poles), Jupiter has one too. But Jupiter’s is much, much more massive and more powerful. “Its magnetic field extends so far into space that, if it glowed in visible light, Jupiter would appear to be twice the size of the full moon in our night sky,” the New Yorker explains.
Juno will study what inside Jupiter creates such a massive magnetic field. But doing so puts the probe in danger.
For Juno to get close to the surface of Jupiter, it had to sneak in where the magnetism is weakest: near the poles. Once inserted near the poles, Juno can orbit underneath the most intense areas of radiation and protect its sensitive electronics.
Juno’s mission is slated to continue until 2018. So this is just the beginning of the insights we’re going to learn about Jupiter.