Everyone knows about Jupiter’s famous Great Red Spot, the centuries-old giant anticyclone on Jupiter’s southern hemisphere 2-3 times the size of Earth. But there are many other smaller (but still huge by terrestrial standards!) storms on Jupiter, the largest of which is Oval BA—also known as the “Red Spot Jr.” The image above shows this approximately Earth-sized anticyclone, imaged by NASA’s Juno spacecraft during its 4th “perijove” close pass on Feb. 2, 2017.
I enhanced the original image from Juno’s Junocam instrument to bring out the structure and colors of the swirling clouds in Oval BA. You can see some bright cloud top domes within the center of the storm itself, the result of “boiling” convection cells not unlike what happens in storms on Earth…except on a much larger scale!
It’s the signature accessory of the largest planet in our solar system: Jupiter’s Great Red Spot, an enormous anticyclone over twice the width of our entire planet. Visible in even modest backyard telescopes, the GRS has been churning away for at least several hundred years. But, based on recent analysis of data gathered by the Cassini spacecraft during its pass by Jupiter in December 2000, the Great Red Spot’s rusty coloration may actually only be skin-deep – a “sunburn” created by interaction between Jupiter’s upper atmosphere and solar radiation.
It used to be said with confidence by even grade-school kids that the largest storm in the Solar System was Jupiter’s Great Red Spot, which has been churning for at least 350 years and could fit three Earths across it. And while it’s true that the GRS is a truly enormous hurricane by Earthly standards, these days it’s not as “great” as it used to be — over the past couple of decades the GRS has shrunk to only about a third of its former size.
“Recent Hubble Space Telescope observations confirm that the Great Red Spot (GRS) is now approximately 10,250 miles across, the smallest diameter we’ve ever measured,” said Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
That equals about 16,500 kilometers, or about one and one-third Earths across. Which is still very big, yes, but nothing compared to what it once was!
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Here’s a great presentation made for the NOAA and NASA Goddard Spaceflight Center about the giant planet Jupiter, part of the Science of a Sphere series. It shows the size and power of the huge gas planet and how it dominates its region of the solar system. Indeed, if it weren’t for Jupiter standing as guardian of the inner solar system life on Earth may very well have never been possible!
Credit: NASA / NOAA / GSFC
This video, made up of 16 images assembled from Voyager 1 data by astro-artist Björn Jónsson and animated by Ian Regan, shows a time period spanning 16 Jupiter days (about 7 days Earth-time) wherein we can briefly observe the dynamics of the different cloud belts and spinning storms in the gas giant’s swirling atmosphere. Especially prominent is the Great Red Spot, a monstrous hurricane in Jupiter’s southern hemisphere three times the size of Earth and over 300 years old. Very cool!
The video is somewhat true-color, although a bit washed-out because Voyager 1’s CCD cameras were not calibrated to detect the color red as our eyes would see it…since Jupiter’s atmosphere has a lot of red in it, the closest approximation to that hue in the image data received is a less intense orange coloration. In other words, Jupiter would actually look a lot more vibrant to the human eye.
Click the video to watch on YouTube and read more about how it was assembled. Great work, guys!! (And be sure to try it in 720p, full-screen too!)
Voyager 1 was launched in September of 1977 and made its closest pass by Jupiter on March 5, 1979. Completing its Jovian encounter in April, Voyager 1 sent back almost 19,000 images of the giant planet and its moons before continuing on to pass by Saturn. It is now the most distant active spacecraft – and man-made object – still sending back data from the edge of the solar system nearly 11 billion miles away.
Credit: NASA / JPL / Björn Jónsson / Ian Regan. Thanks to Emily Lakdawalla for the video.
Skillfully reworked by astrophotographer and Unmanned Spaceflight member Björn Jónsson, this section from a Voyager 1 image mosaic shows the Great Red Spot as it appeared in March of 1979 in amazing detail…with sunlight coming from the right side, the sense of the clouds really being three-dimensional and that you’re looking down through layers and layers of Jupiter’s giant and swirling atmosphere is, to me, simply staggering. It almost looks more like a close-up of a Van Gogh or Edvard Munch painting rather than a churning hurricane over twice the size of our entire planet!
I cropped and did some slight curve adjustments of my own to heighten the detail even further (because I can’t help myself), but be sure to check out the full-sized original, and read the article on Discover Magazine’s Bad Astronomy blog here or on The Planetary Society’s blog here.
“This image looks sufficiently different (and better!) from the old, official versions that in a way I feel like I’m processing stuff from a new planetary encounter when I see this. We will probably not be seeing anything comparable to this until EJSM (or some future spacecraft) starts orbiting Jupiter.”
– Björn Jónsson
Thirty-one years later and we’re still finding new surprises in space exploration data. How great is that!? Superb work, Björn!
Image credit: NASA/JPL/Björn Jónsson