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The Universe
and Beyond

Stars & Gravitation
Class Notes

Universe means: All the matter and energy that exists .

Examples: 1) Stars, Planets, Dust Gases, energy from space

STARS: A body of gasses that give off a huge amount of radiant energy in the form of light and heat.

Except for closeness to Earth the Sun is similar to billions of other stars.

Middle School Science
7,000 Stars And The Milky Way
Credit: Knut Lundmark, Lund Observatory,
Stellar (star) Evolution: - Stars begin as a thing called a NEBULA:

A Nebula is: A cloud of gas and dust usually composed of approximately.

70 % Hydrogen
28% Helium
2% Heavier Elements

Rural Education Chad Williams

Nebular gases have a weak attraction to each other.

An explosion of a nearby star compresses some particles and the Nebula cloud begins to contract. More information on this and the different stages at bottom of this page:
LAW OF UNIVERSAL GRAVITATION:
GRAVITATIONAL FORCE INCREASES AS DISTANCE BETWEEN TWO MASSES DECREASES.
Potomac Montana

Between any two objects that have mass, there exists an attractive gravitational force acting on each object separately. These two forces have the same magnitude but are in opposite directions.

When the two objects have spherical mass distributions (or are point masses), then the gravitational force acts along a line connecting the center of mass of each of the two objects.

FG = Magnitude of the Gravitational Force (N)
m1 = Mass of one body (kg)
m2 = Mass of a second body (kg)
G = 6.672x10-11 N.m2/kg2 (Universal Gravitational Constant)
D2 = Distance between the centers of mass of the two objects (m)


Sir Issac Newton (do you remember his three laws?

Potomac Middle School

Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

The second law explains how the velocity of an object changes when it is subjected to an external force. Another way to say this is acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

The third law states that for every action (force) in nature there is an equal and opposite reaction.

For more explanation check out the Newton Law pages: Explained Here

Astromomy Science Montana Take a look at the life cycle of a star Chad Williams

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