Saturn’s polar vortex changes colors with the seasons
Saturn’s hexagon seen in April.
Storms in space can take many forms.
From Jupiter’s planet-sized cyclones to Earth’s spinning hurricanes, our solar system is filled with raging tempests of all shapes and sizes.
But perhaps the most beautiful weather feature in the solar system is found on Saturn.
The ringed planet plays host to a photogenic, hexagon-shaped jet stream that circles a giant storm in the planet’s north pole.
A new gif showing the movement of the north polar hexagon shows off the Cassini spacecraft’s view of the rose-tinted jet stream on April 25. This was just before the probe made a dive between the 1,500-mile-wide gap between Saturn and its rings.
This isn’t the first time Cassini has snapped pictures of the hexagon.
The spacecraft has taken photos of the storm many times over the course of its more than decade-long mission at Saturn. Comparing the new images with ones taken in 2013 shows exactly how much the planet’s north pole has changed over time.
"In 2013, the entire interior of the hexagon appeared blue," NASA said in a statement. "By 2017, most of the hexagon’s interior was covered in yellowish haze, and only the center of the polar vortex retained the blue color."
Researchers think that the change in color is a result of particles of smog produced as the sun shines more on the region near the summer solstice, which occurred on May 24, NASA said.
Image: NASA/JPL-Caltech/Space Science Institute/Hampton University
A side-by-side of the hexagon in 2013 (left) and 2017 (right).
Even though the hexagonal area around the north polar vortex has changed in color, for some reason, the central vortex itself always remains blue-tinted.
According to NASA, it’s possible that the vortex stays blue because it remains sheltered from sunlight, and therefore particles of smog, as the season changes.
But that’s not the only possibility.
"A second explanation hypothesizes that the polar vortex may have an internal circulation similar to hurricanes on Earth," NASA added. In the eye of hurricanes, descending air clears the sky of clouds and precipitation.
This may be the case with Saturn’s vortexes, too, NASA said.
"If the Saturnian polar vortex indeed has an analogous structure to terrestrial hurricanes, the circulation should be downward in the eye of the vortex. The downward circulation should keep the atmosphere clear of the photochemical smog particles, and may explain the blue color."
Image: NASA/JPL-Caltech/Space Science Institute
Saturn’s short shaddow.
Cassini is continuing to explore Saturn and its many moons as its mission nears its end in September.
Until then, the spacecraft will continue making dives between Saturn and its plane of rings, sending back beautiful images of the world’s clouds, moons and rings along the way.
In September, however, Cassini’s long mission will come to an end when it makes its planned dive into Saturn’s atmosphere, burning up in the process.