Bruce Larsen, age 13, of Duluth, Minn., for his question:
WHO DISCOVERED THE CONSTELLATIONS IN THE SKY?
About 500,000 stars are located in our universe, but only about 9,000 of them can be seen from the earth without a telescope. City lights, unfortunately, act somewhat like the sun in brightening the sky and making it difficult to see the night's stars. Many of the bright ones can be seen, however, and lots of them are part of "sky pictures" called constellations.
We don't know who first discovered the constellations in the sky. But we do know that since ancient times men have been imagining
Names of the constellations are given in Latin, because Latin was once the language of learning. The names of the groups used by the Egyptians, Greeks and other peoples were translated into Latin.
Ancient stargazers named the constellations after certain figures that the stars seemed to form in the sky. Ursa Major, the Great Bear, seems to form a bear, for example.
In 1928 the International Astronomical Union fixed the boundaries of the 88 constellations in the sky. The Greeks recognized and named 48 of them. The Arabs, Egyptians and Babylonians recognized many of the same constellations.
Since the 1700s, astronomers have named the 23 constellations that can be seen in the extreme Southern Hemisphere.
By knowing the position of the constellations in the sky, it is possible to locate planets, stars, comets and meteors. For thousands of years, man has used his knowledge of the constellations to guide himself while on trips over the surface of the earth.
Each constellation has a definite time of the year when it reaches its highest point in the sky. At latitudes too far north or south of the equator, many constellations do not culminate high enough to be seen. The constellations appear to move westward as the earth rotates around the sun. For this reason, certain constellations can be seen only during one of the seasons of the year.
As the earth moves around the sun, some constellations gradually become part of the day sky, and others become part of the night sky.
Astronomers have developed a number of different types of star maps which can be used to locate stars and constellations in the night sky. Ask your teacher or your librarian how you can obtain a sky map. Then go out at night into a clear place where you can find Leo the lion, Orion the hunter, Pisces, Scorpius, the Big Dipper and the Little Dipper, Cassiopeia, Pegasus and other interesting constellations.