Earth and Its Moon Chapter 4 Earth Science
Dec 11, 2015
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
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.
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
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