An orbital sunrise is the natural light display observed in space during low orbit from behind Earth's horizon. Orbital sunrises occur when the orbiting body passes the day-night terminator, roughly every 90 minutes for members aboard the International Space Station An orbital sunrise typically features a thin blue arc which quickly transitions to vibrant orange and red hues due to the effects of Rayleigh scattering Orbital sunrises can also reveal polar mesospheric clouds in the atmosphere.