What scientific discovery was discovered in the 1500s?

The 1500's was considered the Renaissance (although, perhaps late in the Renaissance movement). I'll hit this a little from both ends.

Leonardo da Vinci (1452 to 1519) was considered a great inventor, scientist, and painter. He had several detailed anatomy studies, and made drawings of weapons, "flying machines", helicopters, and bridges. Many of his drawings never were built, or weren't attempted for another 500 years.

Nicolaus Copernicus (1473 to 1543) is often considered the father of modern Astronomy. Aristotle had placed the earth in the center of the universe and the planets and sun orbiting around the earth which didn't fit well. Copernicus changed this with the sun as the center of the universe and the earth and planets orbiting around the sun.

Hans Lippershey (1570 to 1619) Invention of the telescope (1608).

Galileo Galilei (1564-1642). Made a crude water thermometer in 1593.

Used telescope to observe planets. Discovery that the planets weren't just points of light. Discovery of moons around Jupiter (using the telescope above, 1610).