Some stunning recent images of
the atmospheric vortex at the center of Saturn’s north polar hexagon were caught
by NASA’s Cassini spacecraft this week. The images were taken during the latest
of Cassini’s ring-grazing orbits, which have so far produced spectacular
glimpses of Saturn’s rings, and its wonderfully pasta-shaped moons. And now,
this.
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Image: NASA/JPL-Caltech/SSI/Jason Major
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This wouldn’t be the first
time Saturn has displayed uncanny, chameleon-like abilities. In fact, the image
above is pulled from a press release NASA issued last October, which noted a
striking color change across the entire north polar hexagon from 2012 to 2016.
Here’s a GIF that illustrates its evolution over time:
NASA has hypothesized that
the color change between 2012 to 2016 was due to “increased production of photochemical
hazes in the atmosphere as the north pole approaches summer solstice in May
2017.”
In other words, as Saturn’s
north pole tilted sunward, interactions between sunlight and atmospheric
compounds that produce haze started increasing, changing the hexagon’s overall
hue. As Kunio Sayanagi of the Cassini Imaging team noted in 2013, the hexagon
acts as a particle barrier “like Earth’s ozone hole.”
It’s difficult for bits of
the atmosphere to cross in and out, so any chemical changes within the hexagon
tend to stay within the hexagon.
