n. The act of emerging; emergence: chiefly used in contrast with immersion, etc.n. In astron.: The reappearance of a heavenly body after an eclipse or occultation; also, the time of reappearance: as, the emersion of the moon from the shadow of the earth; the emersion of a star from behind the moon.n. The heliacal rising of a star—that is, its reappearance just before sunrise after conjunction with the sun.