EMERSION, in astronomy, is when the sun, moon, or other planet, begins to re-appear, after its having been eclipsed, or hid by the interposition of the moon, earth, or other body.
The difference of longitude is sometimes found by observing the immerfions and emerfions of the first of Jupiter's satellites. The immerfions are observed from the time of Jupiter's being in conjunction with the sun to his opposition; and the emerfion, from the opposition to the conjunction; which two intervals are usually six months a-piece, and divide the year between them. But when Jupiter is in conjunction with the sun, and 15 days before and afterwards, there is nothing to be observed; the planet, with his satellites, being then lost in the light of the sun.
EMERSION is also used when a star, before hid by the sun, as being too near him, begins to re-appear, and to get out of his rays.