Before revision: During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes called the dark segment or twilight URL – appears as a dark and diffuse band just above the horizon, most distinct when the sky is clear.
After revision: During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes called the dark segment or twilight wedge – appears as a dark and diffuse band just above the horizon, most distinct when the sky is clear.