Where does emersion collide?

In astronomy emersion is the moment a star, planet or satellite reappears from behind an occulting body, the end of an occultation or eclipse and the counterpart to immersion (disappearance); its precise timing is used for positional and dimensional work, as in Trunkovskii's photoelectric timing of a lunar occultation during a total eclipse. The referent is a reappearance event in an occultation. Contrast the marine-ecology meaning, where emersion is exposure to air at low tide.[1]

Unit

One emersion event, measured as a contact time.

Recovery means

Time the instant the hidden body's light reappears at the occulting edge.

Measured by

Photoelectric or video occultation timing.

In marine ecology emersion is the period when intertidal organisms are exposed to air as the tide falls, imposing desiccation, thermal and photosynthetic stress, the counterpart to submersion, as in Davison, Johnson and Brawley's finding that tidal emersion inhibits photosynthesis in a brown alga, and Druehl and Green's submersion-emersion sensor. The referent is aerial exposure during the tidal cycle. It shares only the Latin emergere ('to rise out') with the astronomical reappearance.[2][3]

Unit

One emersion period, measured in hours of air exposure per tidal cycle.

Recovery means

Record when an intertidal site is uncovered by the receding tide.

Measured by

Tide-level logging; submersion/emersion sensors; physiological assays.