zodiacal light
zoh-DY-ah-kul
A faint, triangular glow visible on the horizon just after sunset or just before sunrise, caused by sunlight scattering off a vast, thin disk of interplanetary dust orbiting the sun along the plane of the solar system. It is so faint that light pollution renders it invisible to most people alive today. In a truly dark sky, zodiacal light can be brighter than the Milky Way. It is sunlight reflected off dust that has been drifting between the planets since the solar system formed — ancient light bouncing off ancient debris.
Etymology
From zodiac (Greek zōidiakos, the circle of little animals — the constellations through which the sun appears to travel) + light. The glow follows the zodiac because the dust lies in the same plane as the planets.
Notes
Sometimes called "the false dawn" — it can be mistaken for the first light of morning.
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