1.  emersion(n = noun.event) egress - (astronomy) the reappearance of a celestial body after an eclipse;
is a kind of reappearance
is a part of eclipse, occultation
Antonym: immersion

2.  emersion(n = noun.act) emergence - the act of emerging;
is a kind of appearance
Derived forms verb emerge₁, verb emerge₃, verb emerge₂, verb emerge₄, verb emerge₅

1.  The act of emerging, or of rising out of anything; as, emersion from the sea; emersion from obscurity or difficulties. [1913 Webster]
"Their immersion into water and their emersion out of the same." [1913 Webster]

2.  The reappearance of a heavenly body after an eclipse or occultation; as, the emersion of the moon from the shadow of the earth; the emersion of a star from behind the moon. [1913 Webster]

emersion, n.
1 the act or an instance of emerging.
2 Astron. the reappearance of a celestial body after its eclipse or occultation.

Etymology:
LL emersio (as EMERGE)

N  egress, exit, issue, emersion, emergence, outbreak, outburst, eruption, proruption, emanation, egression, evacuation, exudation, transudation, extravasation, perspiration, sweating, leakage, percolation, distillation, oozing, gush, outpour, outpouring, effluence, effusion, effluxion, drain, dribbling, defluxion, drainage, outcome, output, discharge, export, expatriation, emigration, remigration, debouch, debouche, emunctory, exodus, emigrant, outlet, vent, spout, tap, sluice, floodgate, pore, vomitory, outgate, sally port, way out, mouth, door, path, conduit, airpipe, effused, outgoing.