'Eala earendel, engla beorhtast,
ofer middangeard monnum sended...'

'O Earendel, brightest of angels,
sent to mankind over middle-earth...'

The midwinter solstice, the Anglo-Saxon version of 'O Oriens', and the light of Tolkien's Earendil: https://aclerkofoxford.blogspot.com/2013/12/the-anglo-saxon-o-antiphons-o-oriens-o.html

'A light when all other lights go out! And now indeed light alone can help us.'

As it's the solstice: a recent post on a time-haunted year, the dead of winter, and the contested history of Christmas https://aclerkofoxford.blogspot.com/2020/11/times-handiworks-by-time-are-haunted.html

Another connection between Tolkien's world and Anglo-Saxon Advent poetry: Christ the Arkenstone https://aclerkofoxford.blogspot.com/2014/12/the-words-linger-christ-arkenstone-and.html

'prophets of the Lord,
holy ones sage in spirit, spoke to men
often, not once only, of that noble child:
how the precious stone should
come into the world...'

A description of the winter solstice ('winterlica sunstede') in Old English, from Ælfric's De temporibus anni ( http://bl.uk/manuscripts/FullDisplay.aspx?ref=Cotton_MS_Caligula_A_XV f. 145v-6)

As the early dark descends, some old rhymes for 21st December...

St Thomas grey, St Thomas grey,
The longest night and the shortest day.

https://archive.org/stream/englishfolkrhyme00nortuoft#page/455/mode/1up