Constellations look flat, but they are really three-dimensional.
The stars forming a constellation only appear to be close together and on the same plane — like a drawing on a piece of paper. In fact, they may be very far from one another. For example, Betelgeuse in Orion is some 400 light-years distant. Rigel is almost twice as far — about 775 light-years. In the Big Dipper, which is part of the constellation Ursa Major, five of the seven stars are part of a cluster about 80 light-years away, one is in front of the cluster at 70 light-years, and the star at the tip of the handle of the dipper is 105 light-years away.