Joseph Gorecki, age 14, of Nashville, Tenn., for his question:
' WHEN WAS THE FIRST OBSERVATORY BUILT?
An observatory is a building specially constructed for use in making astronomical observations. Modern observatories usually house telescopes, although the term is also sometimes applied to buildings used for observing magnetic or meteorological phenomena. The earliest known astronomical observatories were built by the Chinese and the Babylonians about 2300 B. C.
These ancient observatories were probably little more than high platforms giving unobstructed views of the sky.
About 300 B.C. the most famous observatory of classical times was built in Alexandria, Egypt. It was most likely equipped with instruments, such as the astrolabe, by which the celestial latitude and longitude of a star or planet could be measured. The Alexandria observatory existed for approximately 500 years.
After the beginning of the Christian era, the Arabs established a number of observatories at Damascus and Baghdad. They also built one at Mokatta near Cairo in Egypt about 100 A.D.
The first observatory in Europe was built in 1471 in Nurembern in what is now West Germany.
About a century later, a large and well equipped observatory was built by a Danish astronomer named Tycho Brahe on the island of Ven. Brahe's observatory, in which he lived and worked from 1576 until 1596, was equipped with a large quadrant used in making accurate measurements of the altitudes of celestial bodies.
The observations Brahe made were used by the German astronomer Johannes Kepler in developing his theory of the solar system.
After the invention of the telescope about 1609, a number of new observatories were built in various European cities.
Among the most famous of the early European observatories were the French National Observatory at Paris, established in 1667, and the British Royal Observatory, often called the Greenwich Observatory, founded in 1675. Both are still in existence.
The first observatory to be constructed in the United States was built at Chapel Hill, N. C., in 1831. The Naval observatory at Washington, D.C., was established in 1842. Other famous U. S. observatories are the Lick Observatory, the Mount Wilson Observatory, the Palomar Observatory and the Yerkes Observatory.
A relatively new field of astronomical technology is concerned with study of the universe from a point high above the earth, using equipment carried by balloons, rockets and orbiting observatories. Carrying telescopes, cameras and instruments for special analysis, these vehicles provide a means of studying the stars and planets free of distortion from the atmosphere.
The first space observatory, the satellite Cosmos 215, was launched by the Soviet Union in 1968.