Morwinyon

Morwinyon is a star of Eä, mentioned only in the Tolkien's earliest tales of the First Age as compiled in The Book of Lost Tales.

In that book, Christopher Tolkien identifies this star as Arcturus, the third brightest individual star visible in our Northern Hemisphere.

History
In the account of the fifth chapter, "The Coming of the Elves and the Making of Kôr", the Vala Manwë suddenly became of the awakening of the Elves. Their arrival prompted Varda to create new stars to add to the celestial glory of the earth. At the end of this task, Varda was returning in great haste to Valinor, and she dropped Morwinyon in the west where it blazes high above Arda's edge.

Later in chapter 8, it was said that jewel-makers caught their inspiration from the stars and "...not least did they love Morwinyon of the west, whose name meaneth the glint at dusk." In the commentary in this chapter, Christopher Tolkien notes that Morwinyon was identified in both the Quenya and Gnomish word-lists as Arcturus. Strangely, it is represented as always being in the western sky. Apparently in the ancient mythology of the Elves, not all heavenly bodies moved from East to West.

Etymology
Morwinyon is a Quenya word, the roots of which are moro, meaning "glint in the dark", and gwini - which has a derivative word wintil - meaning "a glint". The Gnomish translation is Morwinthi, probably connected to gwim or gwinc "spark, flash" or gwimla "wink, twinkle".