The Earth, the Moon, and the Sun

Physical Science2011-2012

The Earth in SpaceSection 7-1

Gravity from the Earth-Moon-Sun system directly affects the conditions for life here on

Earth.

The Physical Characteristics of the Earth

• Diameter (12,714 km/7,926 mi.)• Circumference (40,075 km/24,901 mi)• Mass (5.98 x1024

kg/1,130,000,000,000,000,000,000,000 lbs.)• Average distance from the Sun (149,000,000

km/92,384,987 mi.)• Average distance from the Moon (384,400

km/238,855 mi.)

The Earth’s Magnetic Field

The Earth’s magnetic field helps protect the Earth from harmful radiation/energy

from the Sun.

The Magnetosphere

Areas of charged particles (protons and electrons) that circle the Earth above the

atmosphere. The particles are held in place by gravity and are called the “Van Allen belts”.

The AuroraA stream of particles called the “solar

wind” flow through space from the Sun toward the Earth and collide with the

magnetic field that causes them to flow down toward the north and south poles.

The AuroraThe “solar wind” particles then collide with atoms in the atmosphere at the

poles and cause the solar wind particles to give off light.

Aurora Borealis (Northern Lights)

Aurora Australis (Southern Lights)

The Earth’s Orbit around the Sun

The Earth’s Orbit around the Sun

• Elliptical shaped orbit

The Earth and Venus• Same size• Venus has an atmosphere of 96% CO2

creating an average temp of 460 Celsius (860 F)

• Earth has an atmosphere of 0.04% CO2 creating an average temp of 15 Celsius (60 F).

The Earth and Mars• Earth is twice as large• The Earth’s gravity is strong enough to

hold our atmosphere in place, Mars cannot hold one sufficient for life as we understand it

• Average temperature on Mars is -63 Celsius (-85 F)

Size Comparisons

Size Comparisons

Time and SeasonsSection 7-2

People have used the movements of the Earth, Moon, and Sun to measure time for thousands

of years.

Time Zones

• The Earth spins one complete turn in 24 hours, so 360 degrees of motion in 24hrs give you 15 degrees of movement an hour.

• 360/24 = 15• This motion creates 24 time zones of 15

degrees of longitude each.

Longitude

Lines running east to west that when used with lines of latitude help us calculate position on the Earth. GPS

Time Zones

Years and Days

• Rotation measures days (1 rotation 24hrs)• Revolution measures years (1 revolution 365

days)

The Reason for the SeasonsThe Earth is tilted 23.5 degrees

The Tilted AngleThe 23.5 degree tilt causes the angle that

the sun hits the Earth to change throughout the year.

Equinox vs. Solstice

• Equinox (Spring and Fall, equal day and night hours)

• Solstice (Summer and Winter, most hours of daylight and least number of hours of daylight)

The Earth’s MoonSection 7-3

Rotation and Revolution

The moon revolves once around the Earth every 27

days.

How does the Moon affect the Earth?

The Tides

The Pull of the Moon and the Sun

The Surface of the Moon

The surface of the Moon is barren rock, this is how the Earth would look

with no water or plant life

Craters, Maria, and Mountains

Maria (Dark Spots) Regolith (Light Spots)

Asteroid Impact

Origin of the Moon(Disproven Ideas)

• The Capture Theory• The Binary Accretion Theory• The Fission Theory

The Capture TheoryThis theory stated that the moon

formed somewhere else in the solar system and was pulled in by the gravitational pull of the Earth.

The Binary Accretion Theory

The Moon condensed from the same loose space material as the Earth did.

The Fission TheoryA portion of molten material was

ejected from the Earth as it cooled.

Origin of the Moon(Modern Theory)

The Giant Impact Theory