Some centuries ago a planetary scientist by the name of Newton took time off from calculating orbits and wrote an optics primer with a chapter on why some things are highly refractive and others not. As the most refractive liquids at his disposal, olive and clove oil, could be burnt to soot, he correctly surmised that the most refractive solid he knew of might be carbonaceous too, and called diamond : "an unctuous substance much coagulated."
While CO2 gets all the advertising these days it's important to recall that gases in general are refractive too, so planetary optics vary a lot. Carl Sagan deserves credit for discovering that Mars thin ring of atmosphere can concentrate starlight onto a caustic curve at a focal length sometimes approximating the red planet's distance from the Earth, turning its atmosphere into a telescope of sorts.
WEBB WAS IN FOCUS, TITAN'S ATMOSPHERE NOT SO MUCH, AND THE OIL SPILL ON THAT EARTHRISE IS ACTUALLY THE MOON'S SHADOW
The Webb Telescope made a name for itself by finding dozens of galaxies that act as gravity lenses that focus dim and distant objects into brighter Einstein Rings. Now it has turned its golden eye towards Saturn, and what may be the solar system's most refractive satellite atmosphere. The cold, dense, hydrocarbon saturated nitrogen surrounding Titan gives it a climate akin to the head space of a LNG tank. The temperature & pressure are close to the triple point of methane and ethane rain falls into hydrocarbon lakes and seas. In this atmosphere the velocity of light is anything but c . The refraction and color dispersion of the 5% methane atmosphere may warp wide angle views from orbit like a downmarket steampunk camera lens . Stargazing on Titan may be problematic or headache inducing, as the stars ,inconstant in their courses, may part company as they approach the lens-like horizon, and the sun may rise as a blur. There's no mistaking this bizarre blue drop for a pale blue dot.
