nightglow
Etymology
From night + glow.
nightglow means An airglow at night. Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Why this word is great
NIGHTGLOW — [Noun] The faint, continuous photochemical emission from the Earth’s upper atmosphere, a permanent, ethereal shine perceptible only under the full cloak of night. From night (the period of darkness) + glow (a steady light). Unlike “airglow” (the ceaseless atmospheric whisper spanning day and night) or “skyglow” (the synthetic, orange stain of terrestrial light pollution), nightglow is the planet’s specific, nocturnal exhalation. It is the ghost of departed sunlight lingering in the rarefied air ninety kilometres up, the subtle greenish veil over a truly dark desert, and the spectral canvas against which stars are pinned—the planet’s quiet proof that darkness is not an absence, but a different kind of presence.