November 21st is the Gregorian date that Tië eldaliéva (the Elven Path) has assigned this observance (which means it is not one of the seven feasts in Tolkien’s calendar in the Appendices of Return of the King). However, it is also the First Day of Hrivë, the Elven Winter. The Elven Calendar has 6 seasons, with the ones bearing the Solstices being the longest.
At midnight this night, the Pleiades (called Remmirath by the Elves, meaning Netted Road) is directly overhead. The description of the starry sky was shown in The Silmarillion to be very much like this time of year when the Elves were first awoken on Arda (Earth) in the Waters of Awakening, or Lake Cuivienen; thus, Tië eldaliéva’s reason for this observance at this time.
According to these stories, the Elves were awoken before the creation of the Sun and the Moon. The sky then was always a twilight color with stars that were lovingly created by Varda Elentari, the Queen of the Stars, which the Elves loved indeed. In fact, it was the nearby Helluin (Sirius) that was deemed the star that actually awoke the Elves. They arose from the waters and looked up at the stars, and exclaimed “Eä!” which in this case means “Behold!” It was the same word that “The One” Iluvatar used when bringing forth the song of creation that was indeed sung by the Ainur (likened to “angels” and were the “thoughts” of Iluvatar).
It is a time when we reconnect with the Elven Origins, and thereby reconnect to All that Is. Indeed, we remember our source and where we come from.