Understanding the Solar System, Lecture notes of Earth science

Download Understanding the Solar System and more Lecture notes Earth science in PDF only on Docsity!

Understanding the Solar

System

Earth Science

The Geocentric Theory

• (^) The earth is located

at the center of the

universe and all the

planets revolve

around the earth.

Early Greek Astronomy

• (^) States that the

Universe is a perfect

sphere with Earth at

the center.

• (^) Objects in space

also move in perfect

circles.

Aristotle (384-322 B.C.)

• (^) Developed an early model based on the concept of uniform circular motion. He placed the earth at the center of the universe and all of the planets, sun and stars around it.
• (^) When Aristotle lived, if a person could “reason” out why something happened, then you didn’t need to do any experiments to see what would happen.

• (^) Aristotle reasoned that if the earth rotated

about its axis, we should fly off into space.

Since we don't, the earth must be

stationary.

• (^) It would be almost 1900 years before

Galileo introduced the concepts of gravity

and inertia that explain why these effects

are not observed even though the earth

does move.

EARTH at Center!!

• (^) Ptolemy used geometric models to

predict the positions of the sun, moon,

and planets, using combinations of

circular motion known as epicycles.

• (^) An epicycle is an orbit within an orbit
• (^) Having set up this model, Ptolemy then

went on to describe the mathematics

which he needed in the rest of the work.

Ptolemy’s

Model –

Epicycles

Included

The Heliocentric Theory

• (^) The Sun is the center of our solar system

Copernicus

1. Earth is not the center of “everything.”
2. All the planets revolve around the Sun! (heliocentric theory)
3. Stars are very much farther away than the Sun
4. Any motion of the stars is a result of the Earth’s rotation
5. Still used “perfect” circles for the orbits.

Galileo (1564-1642)

• (^) An Italian scientist, Galileo was

renowned for his contributions to

physics, astronomy, and scientific

philosophy. He is regarded as the

chief founder of modern science.

• (^) Galileo was condemned by the Catholic Church for his view of the cosmos based on the theory of Copernicus.

The Great

Compromise

Tycho Brahe

(1546-1601)

Danish Nobleman

Experimentalist &

Observer.

Made very careful measurements of star’s positions. Earth must be stationary.

Tychonic Model

Tycho developed a system that combined the best of both worlds. He kept the Earth in the center of the universe, so that he could retain Aristotelian physics and Ptolemy’s geocentric idea. The Moon and Sun revolved about the Earth, and the shell of the fixed stars was centered on the Earth. But Mercury, Venus, Mars, Jupiter, and Saturn revolved about the Sun.