The celestial coordinate system is a coordinate system for mapping position in the sky which based on the rotation and revolution around the Sun of the planets.The north celestial pole of the equatorial plane is located at the north of the ecliptic plane, where the east, the south, the west and the north are arranged in sequence in clockwise direction. In this connection, the day/night cycle of the planets is the resultant of the superposition of the solar apparent diurnal and annual motions. Three common circumstances were presented in the celestial sphere: the apparent motions of stars and the Sun; the change of the day/night cycle; and the variation of the length of the day/night on planets and satellites in the Solar System, with an emphasis on the special phenomena of Uranus and the Moon.
