Wikipedia: Astronomer

Famous astronomers include:

[John Couch Adams]? (Britain, 1819-1892)
Friedrich Wilhelm Bessel (Germany, 1784-1846)
Tycho Brahe (Denmark, 1546-1601)
[Giovanni Domenico Cassini]? (France, 1625-1712)
[Bonaventura Cavalieri]? (Italy, 1598-1647)
Nicolaus Copernicus (Prussia, now Poland 1473-1543)
Galileo Galilei (Italy, 1564-1642)
Carl Friedrich Gauss (Germany, 1777-1855)
[Asaph Hall]? (USA, 1829-1907)
Hipparchus (Nicea, circa 190-120 B.C.)
Fred Hoyle (United Kingdom, 1915-2001)
[Christiaan Huygens]? (Netherlands, 1629-1695)
Johannes Kepler (Germany, 1571-1630)
[Gerard Kuiper]? (Netherlands & USA, 1905-1973)
Nicolas Louis de Lacaille (France, 1713-1762)
[Johann Heinrich Lambert]? (Germany, 1728-1777)
[Pierre Simon Laplace]? (France, 1749-1827)
Percival Lowell (USA, 1855-1916)
Isaac Newton (United Kingdom, 1643-1727)
Peter Nilson (Sweden, 1937-1998)
Ptolemy of Alexandria (Roman Egypt, c. 85 - c. 165)
Regiomontanus (Johannes Müller, Germany, 1436-1476)
Erasmus Reinhold (Prussia, Germany 1511-1553)
Carl Sagan (USA, 1934-1996)
Clyde Tombaugh (USA, 1906-1997)