Scientists’ Contributions to Scientists’ Contributions to Our Understanding of the Our Understanding of the

Solar SystemSolar System

Assignment #38 – Helio/Geo-Centric Models

Greek Myths tell about…Greek Myths tell about… A god named Helios,

who was “god of the Sun”

A goddess named Gaea (Gee-a), AKA “Mother Earth, “ the protector of Earth and mother of the Titans and humans)

The GreeksThe Greeks Noticed that stars moved

in fixed patterns as they seemed to move across sky – except for 5 that seemed to “wander.”

Determined that these 5 were not stars

Gave us the word “planets” which means “wandering stars”

Believed in geocentric system

geogeo-- meansmeans of Earth; related to Earth

-centric means-centric means

Earth in the center

What does the word ‘geocentric’ mean? Well, if…

and…

then…

geocentric meansgeocentric means

in the center

CopernicusCopernicusPolish AstronomerPolish Astronomer

1500s Believed in

heliocentric system

http://www.bun.kyoto-u.ac.jp/phisci/Gallery/copernicus.html

http://www.aip.org/history/esva/catalog/esva/Copernicus_Nicolaus.htmlFor images of this astronomer, go to:

Source of photo, which is in public domain: Wikipedia

helioshelios-- meansmeans of the sun; related to the sun

-centric means-centric means

sun in the center

What does the word ‘heliocentric’ mean? Well, if…

and…

then…

heliocentric meansheliocentric means

in the centerView an interesting phenomenon in an animation of our heliocentric system: http://www.astro.utoronto.ca/~zhu/ast210/helicentric.html

helioshelios-- meansmeans of the sun; related to the sun

-centric means-centric means

sun in the center

What does the word ‘heliocentric’ mean? Well, if…

and…

then…

heliocentric meansheliocentric means

in the centerView an interesting phenomenon in an animation of our heliocentric system: http://www.astro.utoronto.ca/~zhu/ast210/helicentric.html

Galileo,Galileo,Italian AstronomerItalian Astronomer

1500s and 1600s Believed in

heliocentric system & supported Copernicus

Improved the telescope to view objects in sky

For images of this astronomer and his telescope, go to

http://www.aip.org/history/esva/catalog/esva/Galileo_Galilei).html

Image of Galileo, which is in public domain: Wikipedia

What did Galileo see in the What did Galileo see in the sky to make him believe in sky to make him believe in

heliocentrism?heliocentrism?

2. The moon has mountains, valleys. It isn’t smooth and perfect.

3. Jupiter has moons, so everything does not orbit around Earth.

1. Venus has phases (like the moon), so it must orbit the sun.

1633 at age 70, Galileo had to 1633 at age 70, Galileo had to recant his findings before the recant his findings before the

Church -Church -“must altogether abandon the false opinion

that the sun is the center of the world and immovable, and that the earth is not the center of the world, and moves, and that I must not hold, defend, or teach in any way whatsoever, verbally or in writing, the said false doctrine, and after it had been notified to me that the said doctrine was contrary to Holy Scripture.”

Newton,Newton,English ScientistEnglish Scientist

Recognized that two factors keep planets in orbit:– Inertia

(1st law of motion)

– GravityFabulous pictures on this site: http://www-gap.dcs.st-and.ac.uk/~history/PictDisplay/Newton.html

Source: Wikipedia/pulic domain

1. What does “geocentric” mean? Draw and label a diagram of this model of the solar system.

2. What does “heliocentric” mean? Draw and label a diagram of this model of the solar system.

3. What did the Greeks believe?

4. What scientists believed in the heliocentric model?

Write these questions out and answer them AFTER we read the textbook together in your journal.