EMERSION
, in Astronomy, is the re-appearance of the sun, moon, or other planet, after having been eclipsed, or hid by the interposition of the moon, earth, or other body.
The Emersions and immersions of Jupiter's first satellite, are particularly useful for finding the longitudes of places; the immersions being observed from Jupiter's conjunction with the sun, till his opposition; and the Emersions from the opposition till the conjunction. But within 15 days of the conjunction, both before and after it, they cannot be observed, because the planet and his satellites are then lost in the sun's light.
Emersion is also used when a star, aster being hid by the sun, begins to re-appear, and to get out of his rays.
Minutes or Scruples of Emersion, an arc of the moon's orbit, which her centre passes over, from the time she begins to emerge out of the earth's shadow, to the end of the eclipse.
Emersion, in Physics, the rising of any solid above the surface of a fluid that is specifically heavier than the solid, into which it had been violently immerged, or pushed.
It is one of the known laws of hydrostatics, that a lighter solid, being forced down into a heavier fluid, immediately endeavours to emerge; and that with a force equal to the excess of the weight of a quantity of the fluid above that of an equal bulk of the solid. Thus, if the body be immerged in a fluid of double its specific gravity, it will emerge again till half its bulk be above the surface of the fluid.
