The Big Dipper is an asterism in the constellation Ursa Major (the Great Bear). One of the most familiar star shapes in the northern sky, it is a useful navigation tool.
Asterisms are prominent groups of stars that form patterns but are smaller than, or even part of, a constellation. They are usually easy to find because the stars are close to one another and about the same brightness.
Polaris or the North Star is a star in the night sky that is always in the North. The entire field of stars in the night sky seem to rotate around Polaris.
To locate Polaris, all you have to do is to find the Big Dipper pointer stars Dubhe and Merak. These two stars outline the outer part of the Big Dipper’s bowl. Simply draw a line from Merak through Dubhe, and go about five times the Merak/Dubhe distance to Polaris.
Harriet Tubman used the North Star to aid in helping slaves reach the North.