the moon, Irish, Old Irish ré, luna: *revi, Sanskrit ravi, sun.
II
time, space, Irish ré, Old Irish ré, g. ree, space: *revesi-, the e form of Old Irish rói, *rovesjâ, discussed under raon, q.v. Hence the prep. ré, during, which governs the genitive.
Etymological dictionary of the Gaelic language.
Alexander Gairm Publications.
1982.