Transcript Early Astronomers

Early Astronomers
Tycho Brahe
Galileo Galilei
Johannes Kepler
Nicholas Copernicus
Edmund Halley
Sir Isaac Newton
Nicholas
Copernicus
Polish – 1473-1543
• Concluded Earth was a planet
• Developed the theory that Earth moves around the Sun
with the other planets. Model of the solar system with the
Sun at the center
• He couldn’t prove his theory
• Used circles to predict the orbits of the planets, so the
planets orbits strayed from predicted positions
Tycho Brahe
Danish 1546-1601
• Persuaded King Fredrick the II to build an observatory in
Copenhagen before telescopes were invented (used his
eyesight)
• Designed and built instruments (astrolabes and quadrants)
to accurately measure locations of heavenly bodies.
• Observed a supernova (exploding star)
• Observations, especially of Mars, were far more precise
than any previously made.
Galileo
Galilei
Italian 1564-1642
• Made improvements to the telescope 3 times
magnification to look at the moon, sun and planets out to
Saturn
• Discovered the moon has mountains and craters, the Sun
has sunspots, planets were circular discs, not points of
light, Venus has phases like the moon and that 4 moons
(satellites) orbit Jupiter
• Catholic church believed his theories went against the
bible.
Johannes
Kepler
German 1571-1630
• Discovered 3 laws of planetary motion using Brahe’s data of
Mars while working as his assistant.
1. The path of each planet around the sun is an ellipse
2. Planets travel more rapidly as they near the Sun and slow
as they become more distant
3. Planets orbital period squared is equal to it’s mean solar
distance cubed (T2 = d3). Solar distances of planets can be
calculated
Sir Isaac
Newton
English 1642-1727
• Used Kepler’s work to formulate and test the universal
theory of gravity
Each one of every pair of bodies pulls on the other, the
strength of the pull (gravity) depends on the amount of
matter in the objects and the distance between them
– This explained how planets and their moons could
remain in space while revolving around the Sun.
Edmund
Halley
English 1656-1742
• Calculated the orbit of a comet observed in 1682 and
proved it was the same comet observe in 1531 and 1607.
Predicted the comet would again return in 1758.
• Mapped the stars of the southern hemisphere
• Studied the Moon’s effect on tides
• Measured the distance from Earth to the Sun
• Convinced Sir Isaac Newton to publish his findings