Ann Marie Brown, age 10, of Portland, Me., for her question:

WHO WAS THE FIRST ASTRONOMER?

Primitive men were the first astronomers. Before history was recorded, man learned to measure time by the position of the sun and by the shape of the moon.

A Greek scholar named Eudoxus in about 400 B.C. taught that the heavens revolved around the earth, and Aristarchus in about 200 B.C. held an opposite theory, believing that the earth moved around the sun. Then, for the first time, in about 100 B.C., Hipparchus recorded the positions of the stars, the sun and the moon.

A Greek astronomer working in Egypt about A.D. 150 named Claudius Ptolemy was the world's next great astronomer, and he was followed more than a thousand years later by a great Polish astronomer named Nicolaus Copernicus. In a list of great early‑day astronomers, also include the name Tycho Brahe, the Danish scientist who worked during the late 1500s.