History of AstronomyViews of the Solar System

How did all of SPACE start?No one knows for sure, but it’s

believed that…

Between 10 to 20 billion years ago the entire universe was smashed into a TINY atomic dot. It was so hot that it exploded causing the Big Bang, the birth of the universe.

What did it look like?

At first, the universe was a very hot,fireball of expanding, cooling gas. After about one million years the gas started to condense to form the objects in the sky.

How did different views of solar system and theories about what was going on

in outer space develop and change over the years?

Let’s start with Aristotle…

Aristotle (Air-u-stot-ul)

Aristotle:

The “Grandfather of Science”

Believed in the “Geocentric Model”

Thought the planets and stars moved around Earth in perfect circles

Geocentric Model

“Geo” means Earth

+ “centric” means center

-----------------------------------

= Earth-centered model

Geocentric means everything revolves around EARTH…weird!

What technology did Aristotle use?

• Naked eye

• Observed Earth is a sphere

• No telescopes!

Where was Aristotle from?

When did he make his observations?

Scientist from Greece

350 B.C.

Ptolemy (toll-u-me)

Ptolemy

He believed in the GEOCENTRIC MODEL (Earth-centered)

Predicted the positions the planets are in now

What technology did Ptolemy use?

• Naked eye

• No telescopes!

Where was Ptolemy from?

When did Ptolemy make his observations?

Greek

astronomer

140 A.D.

Geocentric Model

Copernicus (cu-per-ni-cus)

Copernicus• “Founder of Modern Astronomy”

• Believed in Earth’s rotation on its axis once each day

AND

• that Earth revolves around the Sun once a year. This is known as the HELIOCENTRIC MODEL.

Heliocentric Model

• “HELIO” means Sun + “CENTRIC” means center = Sun-centered model

• This was radical, new thinking and not easily accepted by other scientists

What technology did Copernicus use?

Naked eye

Where was Copernicus from?

When did Copernicus make his observations?

From Poland

Lived more than 100 years later, in the 1500s…1543 A.D.

Galileo

Galileo:Discovered Jupiter’s 4 largest moons

Used the telescope to prove Copernicus was correct…the Sun is the center of our Solar System (Heliocentric)

Galileo also…

• Observed that we can see phases like our moon when we look at Venus!

What technology did Galileo use?

TELESCOPE!

Made a telescope that could enlarge objects up to 20 times! WOW…that’s not much… It is less than most binoculars today!

Where was Galileo from?

When did he make his observations?

Scientist from Italy

Lived 100 years after Copernicus – 1610 A.D.

Heliocentric Model

Tycho Brahe (Teek-O)

Tycho Brahe

• Made careful observations

• Recorded positions of the planets

• Believed in Heliocentric Model

What technology did Tycho use?

Naked eye

Tycho’s Observatory

Where was Tycho from?

When did he make his observations?

From Denmark

Late 1500’s

Kepler

Kepler• Used Tycho’s data to find elliptical orbits of

the planets (not perfect circles!)

• Heliocentric Model

What technology did Kepler use?

• Naked eye

• Math calculations

• Telescope

Where was Kepler from?

When did he make his observations?

• From Germany

• Worked in the 1500-1600s