Solar System Organization

Chapters 3 & 4

Forming the Solar System

• Accretion- the process of building something up gradually by the gathering together of small pieces

• Explain how this would build a star?• The solar system?

Gravity

• Newton’s Law of Gravity- stated that every object in the universe attracts every other object

• The strength of the force of gravity between the two objects depends on two factors: the masses of the objects and the distance between them.

What Determines Gravity?

• Earth revolves around the sun in a nearly circular orbit

• Orbit- path of an object as it revolves around another object in space

• What keeps the Earth and the moon from flying off into space?

Inertia

• Inertia- the tendency of an object to resist change in motion

• You feel the effects of inertia everyday when riding in a car and it brakes suddenly. The car stops, but you fly forward (that’s why they invented the seatbelt!)

• The more mass an object has, the more inertia• The more mass and inertia the harder it is for

the object to stop (give an example)

Inertia• Isaac Newton created a law about inertia

• Newton’s First Law of Motion- that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted upon by a force

Models of the Solar System 4.6

• There are two models of the solar system

What is the Geocentric Model?

• Geocentric- Earth is at the center of the revolving planets and stars

• Ptolemy took the geocentric model a little further by saying that moved in circles carried along by larger circles

• This helped to explain what we see in the sky

Geocentric Model

How did the Heliocentric model develop?

• Heliocentric model- sun centered• All planets revolve around the sun• Aristarchus first developed this idea

• Many scientists further developed the heliocentric idea

Heliocentric Model

Heliocentric Model

• Copernicus was able to work out the arrangement of the known planets and how they moved around the sun

• Brahe and Kepler furthered the idea after years of detailed calculations, Kepler found that the obit of each planet is an ellipse ( oval shape)

• Galileo evidence gradually convinced other that the heliocentric model was correct