topic #1: chapter 22 origin of modern astronomy. section 1: early astronomy astronomy is the science...
TRANSCRIPT
TOPIC #1:Chapter 22Origin of Modern Astronomy
Section 1: Early Astronomy• Astronomy is the science that studies the universe.
• The “Golden Age” of early astronomy was centered in Greece.
• Ancient Greeks like Aristotle studied the motion of heavenly bodies by observing and recording the motions.
Section 1: Early Astronomy• Early models of the solar system developed by the Greeks
were geocentric models these models were Earth centered.
• This means that the sun, moon and other planets orbit the Earth.
• Orbit- The path of an object as it goes around anotehr object in space
Section 1: Early Astronomy
Section 1: Early Astronomy• Some ancient Greeks believed in the heliocentric theory this
was the idea that the Earth, moon and other planets orbit the sun.
• There was no way of measuring or collecting data that could support either theory during the times of the ancient Greeks?
Section 1: Early Astronomy
Heliocentric Theory
Section 1: Early Astronomy• Claudius Ptolmey (A.D. 141) defended the geocentric theory of
the universe (which was later proven wrong).
• He believed that the motion of the planets across the nights sky was evidence of the geocentric theory.
• He even accounted for retrograde motion, which is the apparent westward motion of planets against the stars.
• The stars seem to move in an easterly direction but at times the planets seem to move in the opposite direction.
Section 1: Early Astronomy• Retrograde motion
did not help the geocentric theory but it defined the motion of planets “backwards”.
• It was later found that this was due to their own rotations on an axis.
Section 1: Early Astronomy• Polish astronomer, Nicolaus Copernicus (1473-1543) is
credited with discovering the heliocentric model of the solar system because he was able to support his discovery with data and evidence.
Section 1: Early Astronomy• Danish astronomer, Tycho Brahe (1546-1601) advanced the
study by inventing many tools used to observe and measure planetary motion.
• He had an assistant named Johannes Kepler (1571-1630) who furthered his study.
• Kepler is credited with discovering the Three Laws of Planetary Motion.
• These laws identify and define how planetary bodies orbit the sun and each other.
Section 1: Early Astronomy• Kepler defined the shape of the path planetary bodies orbit in
as an ellipse.
• From these laws of motion we have developed a way of measuring distance in space.
• The distance between the Earth and the sun is called an astronaumical unit (AU).
• This is used as the system of measurement when talking about any distance in space.
Section 1: Early Astronomy• Galileo Galilei (1564-1642), an Italian astronomer was the first
person to use the telescope to study space.
• He made many discoveries that supported Copernicus’s heliocentric model of the universe.
Section 1: Early Astronomy• Sir Issac Newton (1642-1727) was a British astronomer who
made arguably the most important discovery in all of astronomy.
• He is credited with defining and proving the existence of gravity.
• Gravity is the attractive force all objects have which determines the motion of objects in space.