Big Dipper vs Great Bear

Big Dipper

name
  • A bright circumpolar asterism of the northern sky, said to resemble a ladle or cart. It is part of the constellation Ursa Major and includes the stars Mizar, Dubhe, and Alkaid. The other stars in it are Alioth, Megrez, Merak, and Phecda. 

Great Bear

name
  • A bright circumpolar asterism of the northern sky, said to resemble a large bear. It is part of the constellation Ursa Major and includes the stars Mizar, Dubhe, and Alkaid. 

How often have the words Big Dipper and Great Bear occurred in a corpus of books? (source: Google Ngram Viewer )