Earth and Its Moon

Chapter 4

Earth Science

The Earth

- The third planet from sun

- Takes 365.256 days to travel around the sun

- Takes 23.9345 hours for the Earth to rotate on its axis

- Has atmosphere of 78% nitrogen, 21% oxygen, and 1% other constituents

- Only planet to harbor life

The Earth’s Magnetosphere

- Caused by the planet’s rapid spin and molten nickel-iron core

- Shields us from almost all harmful radiation

- Protects us from meteors

Van Allen Radiation Belts

-discovered by Explorer 1

-doughnut-shaped region

surrounding equator

-distorted into tear-drop shape by solar wind

-contains rapidly moving charged particles

-auroras are seen

The Moon

•Earth’s only satellite

•Rotational period: 27.32166 days

•Orbital period: 27.32166 days

•Lunar phases: 29.53059 days

•Gravity is one-sixth that of Earth

•No atmosphere

Surface of Moon

*craters

*highlands

*maria

*rille

Origin of the Moon

There are three theories as to how the moon was formed.

1. It was captured by Earth’s gravity.

2. It formed from the same cloud of dust and gas as the Earth.

3. It formed after an asteroid struck the Earth.

PHASES OF THE MOON

Half of the moon is always in sunlight and half is always dark. The lunar view is always changing as the moon moves around the Earth.

New moon Full moon

Waxing crescent Waning gibbous

Quarter moon Last quarter moon

Waxing gibbous Waning crescent

Solar Eclipse

The moon is directly between the Earth and the sun. There are two parts to the shadow – the umbra (inner shadow), the penumbra (outer shadow).

A Lunar Eclipse

The earth is directly between the sun and a full moon. The moon passes through the Earth’s shadow.

TidesTides are caused by the moon’s gravitational pull on the Earth. There are 4 tides during the course of a day – 2 high tides and 2 low tides. Spring tides are higher than usual high tides. Neap tides are lower than usual high tides.

NEIL ARMSTRONG WALKS ON MOON

July 20,1969

USA

Apollo 11

Astronauts on mission

Neil Armstrong (first man to walk on moon)

Edwin Aldrin Jr. (pilot of lunar module “ Eagle”)

Michael Collins -remained in service module

Space travel takes a new form. Now we have 7-man crews.

Satellites

-are built by people

-called artificial satellites

-sent into outer space on the top of a rocket or in the cargo bay of the space shuttle

Types of Satellites

Communication satellites – transmit information around the world

Weather satellites – track weather patterns and conditions

Navigation satellites – used by pilots and sailors

Scientific satellites – add to our knowledge of the universe

Benefits of Space Technology

Light weight tennis rackets

Pacemakers

Microwave oven

Thinsulate clothing

Various medical devices

Heat absorbent packets

Pioneers in Space

January 28, 1986 - Space Shuttle Challenger

Exploded 73 seconds after take off killing all 7 astronauts