At long last, JWST has released its views of Saturn.
Joining previously-imaged Jupiter,
it’s now seen all four of our gas giants.
Saturn, in particular, appears astoundingly different at various wavelengths.
Its hydrogen and helium atmosphere contains traces of ammonia, phosphine, water vapor, and hydrocarbons.
In optical light, Saturn appears a yellowish-brown color.
Clouds — composed of ammonia crystals, ammonium hydrosulfide, and water — preferentially reflect those colors.
But in infrared light, Saturn shows a different side of itself.
Only one-third of Jupiter’s mass, similar-sized Saturn generates little internal heat, appearing far fainter.
Even in infrared wavelengths, Saturn’s appearance is dominated by reflected sunlight.
It’s northern hemisphere summer on Saturn, but Saturn’s north pole currently appears particularly dark.
This suggests that stratospheric aerosols, made of absorptive hydrocarbons, play a major role.
Those aerosols are likely shaped by a planetary-scale atmospheric phenomenon called gravity waves.
But Saturn’s rings, by contrast, appear bright and brilliant.
Composed almost entirely of water-ice, they’re too cool to radiate thermally.
But water-ice is incredibly reflective, even in infrared light.
JWST sees reflected sunlight from Saturn’s rings and in water-ice plumes from Enceladus.
Future JWST views will reveal fainter, thinner, and even more diffuse Saturnian rings.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.