MODELS OF THE UNIVERSE( PHYSICAL SCIENCE).ppt

MODELS OF THE UNIVERSE

1. Models of the Solar System

2. Models of the Solar System
Florida Benchmark
SC.8.E.5.8 Compare various historical models of
the Solar System, including geocentric and
heliocentric.

3. Models of The Solar System
What is a planetary system?
•A planetary system is a star and all of the
celestial bodies that revolve around it.
•An example of a planetary system is the solar
system which includes the sun and the planets
and other celestial bodies orbiting the sun.
Models of the Solar System

4. What is the Center of the Solar System?
•The early scientists, in their attempt to answer this
fundamental question created various models of
the solar system.
•Models, which placed Earth at the center, are
called Earth-centered, or geocentric, models.
Models of the Solar System
http://childrenlearningonline.net/children-science-Lessuniver1.html

5. The Geocentric Model
•The early philosopher and astronomer believed
that everything in the universe is “perfect”; and
that the planets are perfect spheres circling in
perfect circular orbits.
•They believed the Earth was the most important
object in space and therefore assumed it to be the
center of the universe.
Models of the Solar System
http://commons.wikimedia.org/wiki/File:Ptolemaic_system_2_(PSF).png

6. The Geocentric Model
•Aristotle, a Greek philosopher reasoned that if Earth
circled around the sun, then the relative positions of
the stars would change as Earth moves.
•This apparent change in the position of an object
when viewed from different angles or locations on
Earth is known as parallax.
•What Aristotle did not take into account is the fact
that stars are very far away. At such great distance
parallax cannot be observed without a telescope.
Models of the Solar System

7. The Geocentric Model
•The geocentric model of the solar system became
a very important part of ancient Greek Astronomy
beginning in the sixth century B.C.E.
•The Greek philosopher Aristotle (384–322 B.C.E.)
was among the first scholars to put forward an
Earth-centered model of the Solar System.
•His model positioned the moon, sun, planets, and
stars on a series of circles that moved around
Earth.
Models of the Solar System

8. The Geocentric Model
•Aristarchus, a Greek astronomer and
mathematician, is believed to have proposed a
sun-centered model of the solar system.
•Ptolemy an astronomer, geographer, and
mathematician, exploited Aristotle’s Earth-
centered view and developed a complex
geocentric model that was used by astronomers
over the next thousand years.
Models of the Solar System

9. The Geocentric Model
•According to Ptolemy’s model, the planets moved
on small circles that in turn moved on larger
circles.
Historical Models of the Solar System
http://commons.wikimedia.org/wiki/File:Geocentric_system.png

10. The Geocentric Model
•Ptolemy’s “wheels-on-wheels” model seemed to
make sense since it very well illustrated
observations made at the time going back
hundreds of years.
•Scientist for many centuries used Ptolemy’s model
to make predictions of the motions of planets
years into the future.
Historical Models of the Solar System

11. The Heliocentric Model (Sun-Centered)
Historical Models of the Solar System
https://www.flickr.com/photos/nasablueshift/7368861386/

12. The Heliocentric Model
•The model which placed the sun at the center is called
the heliocentric or sun-centered model.
•The Polish astronomer Nicolaus Copernicus watered-
down Ptolemy’s model of the solar system since he
thought the model was way too complicated.
•Although Copernicus adopted Ptolemy’s idea that
planets’ orbits are perfect circles, he however
developed Aristarchus’s primitive sun-centered
model into a well thought out heliocentric model.

Models of the Solar System

13. The Heliocentric Model
•The heliocentric model was fiercely rejected until it was
refined and published by Copernicus and J. Kepler, a
German mathematician, in the late 16th to early 17th
centuries.
•Copernicus’s model eventually became more
widely accepted as it fit observations significantly
better than Ptolemy’s geocentric model.
•Copernicus’s model is known as the most
influential of modern astronomy.

Models of the Solar System

14. The Heliocentric Model
•Galileo Galilei was a scientist who conducted his
experiments in the manner of moderns scientists.
He actually used a very systematic approach very
similar to the scientific methods.
•Galileo’s observations showed that they are other
celestial objects beside Earth with orbiting
satellites.
Models of the Solar System

15. The Heliocentric Model
•His discovery best fit the heliocentric model.
•Galileo also observed that Venus went through
phases similar to the phases of Earth’s moon.
•The observation of these phases was more in line
with the idea that planets revolve around the sun
rather than the Earth.
Models of the Solar System