#atmosphere
The thin shell of air around a planet. Looking straight down we see through little of it, but along the edge we look through a long slant of it, so it glows there: a shader adds light that grows steeply toward the rim, and a halo just outside it from how close each ray passes the planet. It is blue-white where the sun is up and red where the sun is setting, since the long path at dusk scatters the blue away.
1 shader
