Tell Time With a Big Dipper Clock

Every day Earth’s orbital rotation around the Sun.  If we look very closely at the same star every day at the exact same time of day, we see that Earth’s rotation around the Sun has shifted our view of the constellations by a small amount. Each star rises four minutes earlier every day. This includes the stars of the Big Dipper. Over the course of an entire year, the stars and the Big Dipper advance by a complete circle. They come back to the point where they started one year ago.  The only star that seems not to rotate is Polaris - the North Star.  This is because it is inline with Earth's Rotation - due north.

Earth's Rotation

In this manner a clock can be devised for telling the day of the year.

Simulator courtesy of University of Nebraska-Lincoln
Student Project Make a Big Dipper Clock