Earth's shadow

Earth's shadow is the shadow that the planet casts through its own atmosphere and out into space, toward the point opposite the Sun. During twilight, at both dusk and dawn, it can be seen as a dark, diffuse band just above the horizon, most distinct when the sky is clear. The shadow appears as a bluish to purplish band that can stretch across a wide arc of the horizon opposite the Sun, and it is most visible under favorable conditions, such as from an elevated vantage point over water with clear skies and an unobstructed horizon.