The Solar System

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Chapter 3 The Solar System

I. Solar system evolves

A. Sun forms first

1. Collapse of a nebula

2. Nuclear fusion occurs

3. Energy given off as heat and light

B. Planets form

1. Gravity causes clumping of matter

2. Inner planets lose lightweight gases

a. Mercury

b. Venus

c. Earth

d. Mars

3. Some retained lightweight gases

a. Jupiter

b. Saturn

c. Uranus

d. Neptune

4. Satellite of Neptune forms Pluto

5. Smaller clumps become satellites or moons

6. Asteroid belt between Mars and Jupiter

II. Motions of the planets

A. Earth at center

1. Ptolemy's theory

2. Earth at the center of universe

3. All objects orbit around unmoving Earth

B. Sun at center

1. Copernicus's theory

2. All planets revolve around unmoving sun

3. All planets move in same direction

C. Elliptical orbits

1. Kepler's theory

2. Planets have oval orbit (egg-shaped)

D. Inertia and gravity

1. Inertia - planets move in straight line

2. Gravity - pulls planets toward sun

E. Period of revolution

1. Time it takes planet to make one revolution around sun

2. Period of revolution called "year"

F. Period of rotation

1. Time it takes planet to make one rotation on its axis

2. 24 hours in one Earth day

III. Trip through solar system

A. Mercury

1. Has no atmosphere

2. Closest to sun

B. Venus

1. Retrograde rotation

2. Greenhouse effect

C. Mars

1. Reddish color - iron oxide (rust)

2. Has 2 tiny moons - Phobos and Deimos

3. Explored by Vikings 1 and 2

D. Asteroid belt

1. Also known as minor planets

2. Located between Mars and Jupiter

E. Jupiter

1. Atmosphere has thick cloud cover

2. Large magnetosphere, Great Red Spot

3. Has 16 moons - 4 largest discovered by Galileo

a. Io - has active volcano

b. Europa - ice covered

c. Ganymede - has earthquakes

d. Callisto - rocky and ice covered surface

F. Saturn

1. Seven major rings with many ringlets

2. Has huge magnet field

3. Has 21 identified moons

G. Uranus

1. Greenish-blue color

2. Surface of superheated water

3. Rotates on axis at an angle

H. Neptune

1. Mathematician's planet

2. Has 8 moons

a. Triton, 4th largest

b. Orbits Neptune in backward motion

I. Pluto

1. Identified in 1930 by Tombaugh

2. Smallest and least massive planet

3. Has moon named Charon

J. Planet X?

1. Exists beyond Pluto

2. Exerts pull on Neptune and Uranus

K. Comets

1. Oort cloud

a. Collection of ice, gas, and dust

b. Produces "dirty snowball" or comet

2. Comet has 3 parts

a. Nucleus

b. Coma

c. Tail

L. Meteoroids, meteors, meteorites

1. Meteoroids

a. Chunks of metal or stone

b. Orbit the sun

c. Come from asteroid belt or comet that has broken up

2. Meteors

a. Formed by friction

b. Streak of light

c. Known as shooting star

3. Meteorites

a. Meteor that strikes Earth

b. Most contain iron, nickel and stone

L. Life in solar system

1. Earth only planet with life

2. Conditions for life

a. Moderate temperatures

b. Liquid water

IV. Exploring the solar system

A. Rocketry

1. Reaction engine

2. Rearward blast of exploding gases

3. Rocket shoots forward

B. Escape velocity

1. Factors considered

a. Mass of planet

b. Distance of rocket from planet's center

2. Dr. Robert Goddard designed multistage rocket

C. Deep-space probes

1. Mariners

2. Vikings

3. Pioneers

4. Voyagers

Planets in the Solar System Chart