Views of the Solar System History of Astronomy Views 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. https://www.youtube.com/watch?v=kXcVfx2Pw1I

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. https://www.youtube.com/watch?v=GevV1yvMJbc

Geocentric Model

Copernicus (cu-per-ni-cus)

Copernicus Believed in Earth’s rotation on its axis once each day AND “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. https://www.youtube.com/watch?v=GPBB5thPgQE

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. https://www.youtube.com/watch?v=GmwAr54L_pM

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