Peggy Nygren, age 11, of St. Edward, Nebraska, for her question:

Is it true that some stars never rise and set?

It is true that some of our starry constellations never rise and set. Polaris hangs above the North Pole, marking the North Celestial Pole in the sky. In the sky above Omaha, you can see Polaris standing in the same spot, all night and every night. Around it swingy the Big Dipper, the Little Dipper, Draco the dragon, the queen Cassiopeia and the tent shaped constellation of the King Cepheus. These are the north circumpolar constellations. They circle around Polaris once every 24 hours, as the earth rotates. In Nebraska and other temperate latitudes, they never rise and set. Seen from the tropics north of the equator, our circumpolar stars are lower in the sky, and some of them do dip below the horizon.

At the equator, all the stars rise and set. But down in the Southern Hemisphere there is another group of stars that appear in the sky all night and every night. They are centered around the South Celestial Pole. There is no bright star like Polaris to mark ; this spot above the earth's South Pole. The nearest marker is the bright Southern Cross. This and several other starry constellations circle the vacant South Celestial Pole in the sky. South of the tropics, these south circumpolar stars do not rise and set with the nightly parade of other stars.