Emily refers to “midnight” in two of her poems on eclipses: “If He Dissolve Then There Is Nothing” and “Sunsets at Night is natural”
Emily’s brother, Austin, had a lover called Mabel Loomis Todd who published Emily’s poems after she died. Mabel also published a book on eclipses in the same year:

There were four total solar eclipse’s in Emily Dickinson’s lifetime: https://www.greatamericaneclipse.com/19th-century But it seems like Emily only witnessed one at Amherst:

More on the significance of eclipses in her poetry:

https://www.cambridge.org/core/books/abs/emily-dickinson-and-the-religious-imagination/introduction-dickinson-and-religion/AE1FD6C989628333DE0F2BDD2EF923D8
In this poem, Emily Dickinson pretends to be a wife and then comments on this vantage point - allowing her to see the privileges that married women had in that time compared to the “pain” and darkness of living life as a spinster.
She uses the image of an eclipse to represent the positive, sunny outlook married women would have when looking at the dark, painful life of being a spinster. For a deeper analysis of this poem: https://poemanalysis.com/emily-dickinson/im-wife-ive-finished-that/

Interesting that this visual is described as “nature was in an Opal Apron” - significance of lyric “opal” in Taylor’s song Ivy - Opal

Emily compares losing her love to being in darkness - a darkness akin to an eclipse or midnight. More analysis here: http://bloggingdickinson.blogspot.com/2012/05/if-he-dissolve-then-there-is-nothing.html
