THE 1500s (Tycho Brahe uses his eyes)
The Danish astronomer, Tycho Brahe (1546 - 1601) made surprisingly accurate calculations of the position of Mars 20 years before the telescope was invented! In 1576, Brahe set up an observatory in Hven, an island near Copenhagen where he studied the stars for 20 years. Using keen eyesight and large instruments, he calculated the position of Mars to within four minutes of arc.