Galileo’s Contribution to Astronomy: The Telescope

Galileo’s Telescope  Galileo didn’t actually invent the telescope –Terrestrial version was invented in the Netherlands by spectacle makers (Hans Lippershey, Zacharias Janssen, and Jacob Metius)  He did, however, improve upon the design in 1609  Also first to point toward the night sky (only his improvements made this possible)  “Telescope” (Greek for “far seeing”) was first coined by Greek mathematician to refer to Galileo’s device

Support for Heliocentric Model  Phases of Venus: –Because Galileo observed all phases of Venus, it must orbit the sun all phases all phases –Such an observation was impossible in the geocentric model of Aristotle or Ptolemy impossible Venus photo credit: Doug Anderson, Shoestring Astronomy

 Moons of Jupiter: –Galileo observed the 4 largest moons of Jupiter and traced their orbits around this gas giant –This provided proof that bodies orbited that bodies orbited objects other than objects other than the Earth the Earth Jupiter photo credit: Doug Anderson, Shoestring Astronomy Support for Heliocentric Model

Other Contributions: The Moon  Galileo first to report craters and mountains on the moon –Moon not perfect sphere like Aristotle claimed

 First to observe rings of Saturn but was confused by their appearance and couldn’t explain them Other Contributions: Saturn

 Even small telescope allows one to distinguish individual one to distinguish individual stars out of ‘milky’ cloud stars out of ‘milky’ cloud Other Contributions: The Milky Way

 Galileo was one of first in Europe to observe sunspots  Made detailed drawings  Argued sunspots were actually on sun and not satellites of the sun  Further evidence against Aristotle’s view that everything in the heavens was perfect Other Contributions: Sunspots