Lunar Eclipse, Donald Margulies’s 2023 play now receiving a Second Stage Theater production (at Signature Center), opens with one of the two characters, George, sobbing alone. George is a farmer in his 70s, sitting in darkness in a field in western Kentucky, where he is soon joined by his wife, Em, to watch a lunar eclipse. George and Em will not simply observe the overnight event: they will overcome George’s gruff exterior and look back over the course of their life together, facing difficult subjects, including the death of a child, and ultimately reaffirming their connection.