I recall learning about King Arthur in reference to Ursa Major...
From wikipedia
Some scholars have suggested that is relevant to this debate that the legendary King Arthur's name only appears as
Arthur, or
Arturus, in early Latin Arthurian texts, never as
Artōrius (although Classical Latin Artōrius became Arturius in some Vulgar Latin dialects). However, this may not say anything about the origin of the name
Arthur, as
Artōrius would regularly become
Art(h)ur when borrowed into
Welsh.
[9]
Another possibility is that it is derived from a Brittonic patronym
*Arto-rīg-ios (the root of which,
*arto-rīg- "bear-king" is to be found in the Old Irish personal name
Art-ri) via a Latinized form Artōrius.
[10] Less likely is the commonly proposed derivation from Welsh
arth "bear" + (g)wr "man" (earlier
*Arto-uiros in Brittonic); there are phonological difficulties with this theory - notably that a Brittonic compound name
*Arto-uiros should produce Old Welsh
*Artgur and Middle/Modern Welsh
*Arthwr and not
Arthur (in Welsh poetry the name is always spelled
Arthur and is exclusively rhymed with words ending in
-ur - never words ending in
-wr - which confirms that the second element cannot be
[g]wr "man").
[11][12]
An alternative theory, which has only gained limited acceptance among scholars,
[13][14][15][16][17][18] derives the name Arthur from the
Latin Arcturus, the brightest star in the constellation
Boötes, near
Ursa Major or the Great Bear,
[19] which is the
latinisation of the
Greek Αρκτοῦρος (
Arktouros) and means "Guardian of the Bear",
[20] ultimately from ἄρκτος (
arktos), "bear"
[21] + οὖρος (
ouros), "watcher, guardian".
[22] Classical Latin Arcturus would also have become
Art(h)ur when borrowed into Welsh, and its brightness and position in the sky led people to regard it as the "guardian of the bear" and the "leader" of the other stars in Boötes.
[23]
A similar first name is
Old Irish Artúr, which is believed to be derived directly from an early Old Welsh or
Cumbric Artur.
[24] The earliest historically attested bearer of the name is a son or grandson of
Áedán mac Gabráin (d. AD 609).
[25]