The University of Texas at Arlington

The University of Texas at Arlington

The Planetarium at UT Arlington

The Planetarium at UT Arlington

The Big Dipper

Ancient astronomers believed that the Earth was motionless and at the center of the Universe. To the ancients the sky, which surrounds the Earth, was like a great sphere with starry decoration. There are approximately 200 billion stars in our galaxy, the Milkyway. The stars in our night sky are just the ones that are bright enough or close enough for us to see. Ancient astronomers connected bright stars with imaginary lines, called constellations. There are 88 constellations in the entire sky, though some are never visible to us in Texas. Among many stars in the night sky, one of them, just by chance, is located in a very special location almost directly above the Earth's North Pole. It is Polaris, the North Star.

But, how do we find the North Star among the night's stars? Here is a trick:

First, you need the find the star pattern called the Big Dipper (see below). It consists of seven bright stars (of course, there are no lines between stars in the actual sky). Three bright stars form the handle of the dipper, and four stars mark the cup, or bowl. On the dipper's cup's edge, there are two bright stars called Merak and Dubhe. Draw an imaginary line starting from Merak to Dubhe, and keep going. Keep going approximately five times the distance between Merak and Dubhe; you will find another star, not as bright as Merak or Dubhe, but brightest in its vicinity. That is the North Star! It is not the brightest star in the sky, is it? Its importance is due to its position; it is almost directly above the Earth's North Pole. As a consequence of its position, Polaris does not seem to move. It is close to the same position all night long and all year long. By finding the North Star you will always be able to find North and your directions at night.