Jupiter Archives - The Spacewriter's Ramblings

Tracking an Ancient Storm

Jupiter is an amazing sight — even in our night skies. Sure, it looks like a bright dot of light, but you can explore it with binoculars or a reasonable backyard-type telescope pretty easily to spot some details. With the binos, you can find the four largest moon. The telescope will give you a hint of the most amazing storm in the solar system: the Great Red Spot. This giant windstorm has been whirling around the planet for hundreds of years. Its size changes over time, from a whopping three Earths across to a mere one Earth-wide storm. The color shifts, too. It used to be much redder, now it’s more of an orange-pink. You can detect all those changes from Earth, but to get the real story on the Great Red Spot, it’s necessary to look at spacecraft views.

Juno Zeroes in on the Red Spot

The Great Red Spot on Jupiter — This enhanced-color image of Jupiter’s Great Red Spot was created by citizen scientist Jason Major using data from the JunoCam imager on NASA’s Juno spacecraft.
The image was taken on July 10, 2017. Click to enlarge.

For more than a year, the Juno spacecraft and its ever-busy JunoCam have been circling the planet and sending images and data about Jupiter back to Earth. The views have been fantastic. Image after image shows swirling cloud decks, belts, and zones. One target has always been the Great Red Spot, so in early July 2017, the spacecraft swooped low over the planet to get a closer look. The raw images revealed a little of the complexity of the storm, and image processing by qualified citizen scientists brought out the rest. Couple that with data from the craft’s other science instruments, and the spot turns out to be a trove of information. It will answer questions about the longevity of this storm, the processes that formed it, and perhaps even why it seems to shift size and change color.

There are some clues to the changes provided by the chemistry of the clouds that make up the spot. They contain ammonia, ammonium hydrosulfide, and water (plus traces of other gases). Somehow the chemical reactions in these clouds are involved in the changing colors, although it’s not clear what reaction causes the shift. The planet is also bombarded by cosmic rays and has its own highly charged radiation environment. So, could those together explain why the Great Red Spot (sometimes pinkish orange) is as colorful as it is? Planetary scientists are still trying to figure that out. The Juno measurements may help solve the puzzle, and mission scientists are working on its data now.

The Great Red Spot’s Structure

Just by looking at the images of the spot, you might conclude that it’s about the same altitude as the rest of the clouds. Turns out that’s not quite right. The spot is actually some kilometers higher in the atmosphere than the clouds it appears to be a part of; it’s also colder. It whirls around the planet about once every six Earth days and is a very stable type of storm. No one is sure how long it will last, although it has been observed from Earth since the 1800s. So, it’s a long-lasting, color-changing storm blasting its way through a giant planet’s atmosphere. The more we look at it, the more we learn about Jupiter’s atmospheric dynamics (that is, its motions and changes).

After the Great Red Spot Flyby, What about Juno?

The Juno mission is slated to do 37 orbits around Jupiter. It arrived at the giant planet in summer 2016 and began its long, looping orbits right away. Its nominal mission should be done by mid-September 2017. Any extra time after that will be used to do more imaging until the instruments fry in Jupiter’s strong radiation belts, or fail for some other reason. The spacecraft will be deorbited into the Jovian cloud tops after that, plummeting in sometime during 2018 or 2019. Its mission is to study the planet, help determine more details about its composition, measure the magnetic field and gravity, and look for more clues about how the planet formed and evolved. While the general idea is that Jupiter is largely a gas-rich world, current theories also suggest it has more hidden than we know about. That includes a rocky interior about the size of our planet, and it may harbor significant reserves of water well beneath the cloud masses. Here’s hoping that Juno’s mission data will help solidify our understanding of Jupiter and its active atmosphere.

An Epic Approach to Jupiter, as seen by Juno

A view of Jupiter and its largest moons, taken by Juno on June 21, 2016, inbound.

When the Juno mission arrived at Jupiter on July 4th, 2016 and executed a tricky orbital insertion maneuver around the giant planet, it was as epic an achievement as any legendary god or hero or heroine of ancient times could hope for. The science team celebrated with a short video that showed a time-lapse of Jupiter’s moons in orbit around the planet as the spacecraft approached. It’s a three-minute-long timelapse covering a 17-hour period a few days before arrival at Jupiter. As I watched, it really felt like I was on the bridge of a spacecraft approaching the planet. But, listening to the video was a much more visceral experience because of the music and the history it evokes.

Jupiter Orbital Insertion: Historical Roots

The music bed on this video is by Vangelis, created for the movie Alexander. The piece is called “Titans”, named for the divine beings who eventually gave birth to the gods Zeus, Hades, Poseidon, Hera, Hestia, and Demeter. In the Greek tradition, Zeus was the mightiest of the gods, and as the great leader Alexander the Great knitted together his 4th century (BCE) empire, Zeus went along for the ride to confer kingship and greatness. In later traditions, the Romans (who were once part of Alexander’s vast empire), renamed Zeus as “Jupiter” and eventually that name was assigned to the mightiest planet in the solar system.

Alexander the Great spread Hellenistic art and culture across much of the known world in his day as he conquered country after country — from India through the Middle East to Africa and parts of Western Europe. Due to his rule, the influences of the Greeks, along with other cultures he eventually assimilated into his empire, are still seen today in the names we use for the stars and planets. Good examples are Betelgeuse (from the Arabic) for the bright star in Orion’s shoulder and, of course, Jupiter (the romanized Zeus) for the planet.

As I listened to the music in the video and watched the approach to Jupiter as captured by the JunoCam, it simply felt right to combine the two. Exploration was at the core of Alexander’s “mission” all those centuries ago, and now the exploration of a world named in the tradition of a great deity inspired by Greek mythology carries on that tradition of seeing “what’s out there.”

Give the video a watch a few times — with and without the music. It begins with the view that Alexander, Galileo, you and I can see of Jupiter in the night sky. And then… it changes to something only a spacefaring civilization would recognize: the view you would see if you were about to achieve standard orbit around a distant world.

Juno’s journey is, as I said above, as epic as anything the heroes and heroines of old achieved in antiquity. And, as you watch the Jovian moons orbit — from innermost volcanic Io and ice-crusted ocean world Europa to massive Ganymede heavily cratered Callisto — think about this: those motions are what Galileo first glimpsed from his hillside in Padua, Italy in 1610. He watched as they changed position around Jupiter in just a few nights, and that opened his eyes to something no one had quite realized before: that the universe is in motion. It’s not moving around Earth — instead, it moves in a self-consistent way that puts planets around stars, stars circling in galaxies, and galaxies orbiting in fantastic dances within their clusters. His was a small observation, but it forever changed our understanding of our place in the cosmos. Earth was not the center of the universe.

Juno Changes our View Again

Juno shows us what Galileo saw, if imperfectly at first. As scientist Scott Bolton pointed out to us right after Juno achieved its orbital insertion, watching these worlds orbit Jupiter illustrates the motion of nature’s harmony. Appreciating that harmony is a huge part of “doing” science, and if it stirs up some feelings of awe and wonder along with some inspiring music — well, it’s all part of the deal we make when we study the cosmos.

The Spacewriter's Ramblings

Category Archives: Jupiter

Juno Explores the Great Red Spot on Jupiter