(Also Suen, Sin, Ashgirbabbar or Asimbabbar)
"Lord of Destiny"
"Shining Boat of Heaven"
"The Mighty One"
Nanna was a Sumerian-Babylonian moon god who ruled the calendar, fixed the seasons, acted as a vegetation deity and was the patron god of fertility. He was the chief astral and tutelary deity of Ur, having been appointed king of the city by An and Enlil. Nanna’s chief cult centers were at Harran and Ur, where he established the third Ur dynasty by appointing Ur-Nammu as his mortal representative on earth.
This deity was typically depicted as an old man with a shining blue and white beard. The crescent moon was his weapon and the full moon his crown. Less often he was described as a fierce thick-horned bull with perfect legs that had a blue bird on its back. Each night Nanna would climb into his crescent-shaped boat and sail across the skies. He was believed to be wise and secretive, measuring time with his phases. Nanna was the enemy of the wicked, for his light would reveal their wrongdoings or evil natures, but he also blessed the city that housed his temple by raising the marsh waters so the cattle could drink. He thus ensured that Ur would have an abundant supply of food.
Nanna was conceived when Enlil, the air god, raped his bride-to-be, Ninlil, the grain goddess. As punishment, Enlil was condemned by the other gods to life forever in the underworld. Ninlil, to allow Enlil to witness the birth of his child, followed him, which might have condemned Nanna to life in the world of the dead. But Enlil and Ninlil conceived again and offered their next three offspring to the gods of the underworld, allowing Nanna to ascend into the heavens.
He was married to Ningal the "Great Lady" and they had three children: Utu (Shamash), Ishkur (Nusku) and, in later times, Inanna (Ishtar). With Shamash and Hadad, Nanna completes the second triad of Mesopotamian gods. Once a month he travels to the underworld to rest and to decree the fate of the dead. In the Sumerian Lament, Nanna eventually abandons Ur. After falling into poverty due to lack of sacrifices and worshippers, he pleads with Enlil for the return of the city and his request is granted.
Note:
Sin is the Akkadian name for the moon god.
Sources:
http://www.pantheon.org/
http://members.bellatlantic.net/~vze33gpz/sumer-faq.html
http://www.geocities.com/Athens/Oracle/4855/lament.htm