Transcript Cool Dudes of Astronomy!

Cool Dudes of Astronomy!
a.k.a A brief history of astronomy
Ancient Greeks
• Observed patterns in
the stars that didn’t
move or change- the
stars moved, but
stayed in the same
position relative to
each other.
• Observed 5 points of
light that seemed to
wander among the
stars – planets
(wandering star)
• Mercury
• Venus
• Mars
• Jupiter
• Saturn
Earth was the center of the
universe
geocentric
Greek for
Earth
center
http://csep10.phys.utk.edu/astr161/lect/retrograde/aristotle.html
Ptolemy
Curt Suplee, Milestones of Science p.24
• AD 140
• Greek Astronomer
• Earth is the center of
a system of planets
• The planets move on
little circles that move
on bigger circles
around the earth
http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub1.htm
• This vision of the
Ptolemaic universe
from a 1660 celestial
atlas, shows the
position of the Earth
surrounded by the
celestial circles
• These ideas lasted for
1400 years!
Curt Suplee, Milestones of Science
p.24-25
Copernicus
• Believed the sun was
at the center of the
universe
• Heliocentric
Sun
• His work was
published in1543 –
while he was on his
deathbed!
Galileo
• ~100 yr after
Copernicus
• Observed 4 moons
revolving around
Jupiter
• Observed Venus has
phases like our moon
Galileo cont.
Neither of these observations can be explained
with Earth at the center, therefore the sun is at
the center! Copernicus was correct!!
Galileo believed the orbits are circles
Tycho Brahe (TEE koh BRAH uh)
1546-1601
• Danish Astronomer –
made very careful
observations of the
planets for almost 20
yr.
Johannes Kepler
1600’s
• Analyzed Brahe’s
data
• Discovered the orbit
of each planet is an
ellipse.
Sir Isaac Newton
• Inertia and gravity combine to keep the
planets in orbit!