Saturn has a 15 year "day / night" cycle, so when Voyager first took pictures of the hexagon nearly 30 years ago, it was taken in visible light because the Sun was illuminating Saturn's north pole way back then.
Now as the hexagon emerges from the night into the daytime of the "visible light" world of Saturn once again:
After waiting years for the sun to illuminate Saturn's north pole again, cameras aboard NASA's Cassini spacecraft have captured the most detailed images yet of the intriguing hexagon shape crowning the planet.(NASA). Previous Cassini images had to be taken with the infrared cameras because the north pole of Saturn was covered in darkness, in terms of visible light.
As it turns out, these new photos have not accomplished much toward solving this mystery within the Saturn equation, in fact, it may have increased the mystery a bit.