What exactly is "noonday night"?

In answering the question Is there a term for “midnight” that is like “noon”, I came across the phrase noonday night listed as a synonym for midnight in my copy of Roget's International Thesaurus—attributed to Longfellow. I included the reference in my answer, but after reading the passage more carefully, I'm not so sure it is referring to the middle of the night. Searching this phrase turns up many usages by other authors, but I'm unable to determine from them what exactly is being referred to.

I'm wondering if it could be a description of an eclipse, or some permutation of the midnight sun phenomenon. Can anyone offer some insight? What did this phrase originally mean and when was it first used?

Solution 1:

The Longfellow quote refers to the passage in the Iliad (which of course you remember), when one of the gods causes a thick fog to cover the battlefield at midday. www.hellenica.de says

Ajax's prayer to Zeus, to remove the fog which has descended on the battle - even if the Greeks are destined to lose - to allow them to die in the light, has become proverbial.

So "noonday night" is no more an idiom than Koestler's "Darkness at Noon": it's just an expressive description.

Solution 2:

It could be a description of an eclipse, or a terrible storm that darkens the midday sky as if it were night.

Supporting this interpretation is a Sir Richard Blackmore quote in the 1710 The Art of English Poetry by Edward Bysshe

A suddain Storm did from the South arise,
And horrid black begun to hang the Skies:
Low-bellying Clouds soon intercept the Light,
And o'er the Sailors spread a noon-day Night..

This verse is quoted again in one of the later editions of De rarum natura and later in A complete edition of the poets of Great Britain (1795) by Robert Anderson.

There is little context in the Longfellow poem, 'Supernatural darkness' also does not imply night-time. It appears to be a mistake in Roget's Thesaurus.

Solution 3:

In Benny Hester's 1990 Rubber Canoe, lyrics:

It's the dead of the night

Just an L.A. night
New Orleans night
It's a New York night
Miami night

Call it a noonday night

As I found out, "Dead of night" and "noonday night" are synonyms, maybe refer to night times are filled by many mysterious scary things that we are not able to see.

Solution 4:

Well, since noonday is a synonym for noon, noonday of night may be a synonym for midnight. Although I haven't found any solid proof for it, except for this (and it's noon of night, not noonday of night).

Interestingly, I've also found this definition of noonday night:

°A flavored sugar preparation, used for icing cakes.

°Dark chocolate.