I look out at night and see Jupiter and wonder how much we don’t know about the solar system’s biggest planet. Scientific investigation increases our knowledge of the universe but never reaches an endpoint. Who would want it to? There’s an infinite complexity to everything we might investigate, and the hunt’s half the fun. Always another layer, another surprise.
I smile whenever I read that a new study “changes everything.” Some of that’s breathless hype, but change is part of the game when as we come come closer to understanding how things work in the world. Whether you’re a scientist or just someone who appreciates the results of science, however tentative in places, you can revel in the study and appreciation of the natural world as long as you live. Which makes me want to live forever.
Good examples of new and unexpected discoveries are happening right now at Jupiter. NASA’s Juno spacecraft has been monitoring the planet from up close during each of it long-winded orbits, gathering information about its deep interior, stripey clouds and monster magnetic field. Like Earth, Jupiter’s a planet-sized bar magnet with north and south magnetic poles and an invisible magnetic field that controls the motion and direction of atoms and ions (an atom that’s gained or lost an electron) that stray by.
Thanks to Juno we’re discovering that Jupiter’s magnetic field is stronger and more irregular than first thought. The strength of the magnetic field was previously estimated to be about 5 gauss compared to Earth’s 0.25 to 0.60 gauss at the surface, but Juno found that it might be as high as 8-9 gauss. It also dips in intensity over different regions of the planet, indicating that it may not originate in Jupiter’s core as does Earth’s field but higher up closer to the surface. That would be, well … weird.
Scientists had also assumed Jupiter internal structure was uniform. That deep beneath cloudy atmosphere, maybe halfway to the core, immense pressure and heat turned hydrogen gas (Jupiter’s main ingredient) into a metallic liquid that conducts electricity just like a metal. Helium, a heavier element, separates from the hydrogen and rains down towards a deeper layer of hydrogen at the center of which is a small, solid core composed of we-don’t-know-what-yet 43,000 miles down. But Juno’s data indicates that the interior isn’t so cleanly divided as thought, and that the core isn’t solid but “fuzzy” and mingled with the overlying, sloshy hydrogen.
Even the planet’s clouds are yielding surprises. We’ve known for a long time that Jupiter has clouds made of ammonia (pew!), but Juno found there’s a dense, deep zone of ammonia gas around the equator which no one expected. Also the amount of ammonia varies across the atmosphere.
“We’ve known there’s a spike at the equator, but the new microwave data is showing that the spike goes way, way down into the abyss, 300 km (186 miles) below the cloud,” said Leigh Fletcher of the University of Leicester, UK. “It suggests ammonia is being distributed by a weather system that penetrates much deeper than anyone expected.”
There much more to come. Juno’s next closest approach to Jupiter will be on May 19 and include a flyover of the Great Red Spot, Jupiter’s most distinctive feature. What new befuddlement will find there?