The Valacirca, or Sickle of the Stars, was a constellation consisting of seven stars set in the sky by Varda as a warning to Melkor and his servants, which also precipitated the awakening of the Elves. It may have stood as the symbol of Durin, and can be seen on the doors of Moria, though this is unclear.
Other names include Burning Briar (the Hobbits' name for it), Durin’s Crown, Edegil, Otselen, the Plough, Seven Butterflies, Silver Sickle, Timbridhil, and the Big Dipper/Ursa Major; the Men of the Northlands called them "the Wain."
Quenya: "Sickle of the Valar"
In Sindarin, the name is translated as Cerch i-Mbelain.