Appulse is an astronomical term that refers to the very near approach of one celestial object to another, as seen from a third body. Usually it refers to the close approach of two planets together in the sky, or of the Moon to a star or planet as the Moon follows its monthly orbit around Earth, as seen by an observer located on Earth. An "appulse" can also be referred to as a conjunction. A giant Hubble mosaic of the Crab Nebula, a supernova remnant. ... The eight planets and three dwarf planets of the Solar System. ...

Where the celestial bodies come so close together that one actually passes over the other, the event is known as an occultation. In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ...