Earth and its Moon

1
Earth and its Moon
2
The Earth in Space

• The Earth revolves around the sun.
• The Earth rotates on its axis.
• These two combined movements affect both day and
  night and the seasons on Earth.

3
Day and Night

• The Earths rotation causes day and night every
  24 hours.
• The Earth rotates in a counterclockwise pattern (
  west to east) causing the sun to appear to rise
  in the east and set in the west.
• Since the Earths axis is tilted when the North
  Pole is leaning toward the sun, the South Pole is
  leaning away.
• The hemisphere that leans toward the sun has long
  days and short nights.

4
A Year on Earth

• The Earth takes 365.25 days to complete the
  revolution around the sun.
• An extra day is added to the calendar every four
  years in February.
• This is called a leap year.

5
Seasons on Earth

• The Earth has four seasons winter, spring,
  summer and autumn.
• Five of the other planets, Mars, Saturn, Uranus,
  Neptune and possibly Pluto.
• The other planets, Mercury, Venus and Jupiter, do
  not have seasons since they are not tilted on
  their axis.

6
Seasons

• When the Northern Hemisphere is tilted toward the
  sun, that part of the Earth has summer since the
  suns rays are more direct and the days are
  longer.
• At the same time, the Southern Hemisphere is
  tilted away and has winter.
• Summer and winter are not affected by the
  distance from the sun.

7
Solstices

• Summer begins in the Northern Hemisphere on June
  20 or 21.
• The summer solstice is the longest day of the
  year.
• The winter solstice is the shortest day of the
  year.
• When the Northern Hemisphere has the longest day,
  the Southern Hemisphere has the shortest day.

8
Equinox

• Twice a year neither hemisphere is tilted toward
  the sun. These times are known as equinoxes.
• Spring begins on March 20 or 21, the vernal
  equinox.
• Autumn begins on September 22 or 23, the autumnal
  equinox.

9
A Magnet in Space

• The Earths magnetism is probably the result of
  movement of the materials in the Earths inner
  core, which is made mainly of iron and nickel.
• The Earth is surrounded by lines of force.
• The magnetic poles are not in the same location
  as the geographic poles.

10
Magnetosphere

• The Earths magnetic field is called the
  magnetosphere.
• The magnetic field starts at an altitude of 1000
  km and extends to an altitude of 64,000 km on
  the side facing the sun.
• On the side facing away from the sun, the
  magnetosphere extends in a long tail caused by
  solar winds blowing away from the sun.

11
Van Allen Radiation Belts

• Two doughnut shaped regions of charged particles
  are formed as the magnetosphere traps some of the
  particles in the solar wind.
• The outer belt contains mostly electrons, or
  negatively charged particles.
• The inner belt contains mainly protons, or
  positively charged particles.

12
Auroras

• Charged particles that are trapped by the Van
  Allen belt travel along line of force to the
  Earths poles.
• Here they collide with particles of the upper
  atmosphere and produce an aurora.
• The aurora borealis is located at the North Pole
  and the aurora australis is at the South Pole.

13
The Earths Moon

• Neil Armstrong was the first man to step on the
  moon.
• Buzz Aldrin and Armstrong landed on the moon in
  the lunar module, the Eagle.
• Michael Collins, stayed in the command module,
  the Columbia.
• By 1973, 12 Americans had explored the moons
  surface.

14
The Moons Characteristics

• The moons diameter is 1/4 of the Earth.
• The moons gravity is 1/6 of the Earth.
• The moon is 384,403 km from the Earth.
• The moon does not have an atmosphere or weather.
• The temperature is extreme from 100 degrees
  Celsius to 175 degrees.

15
Composition of the Moon

• Instruments have measured moonquakes.
• The crust is 60 km thick.
• Beyond the crust is a dense layer of rock that is
  800 km thick.
• The central core is made of melted iron.

16
Features of the Moon

• In 1609, Galileo looked at the moon with a
  telescope. He called the lowlands, Maria.The
  highlands reach to a height of 8 km.
• Most of the craters are in the highlands. One of
  the largest is Copernicus, which is 91 km in
  diameter.
• Most craters were formed by meteorites.
• Rilles, evidence of volcanic activity, crisscross
  the surface.

17
Movements of the Moon

• Perigee is the point of the moons orbit
  closest to the Earth. The apogee is the point of
  the moons orbit farthest from the Earth.
• The moons period of rotation is the same as the
  period of revolution so the same side of the moon
  always faces the Earth.

18
Origin of the Moon

• One theory states that the moon was formed
  millions of kilometers from the Earth and
  captured by its gravity.
• The moon may have been formed in the nebular
  cloud in which the Earth formed.
• The moon may have been born when a giant
  asteroid struck the Earth and tore a huge chunk
  away, leaving a hole.

19
The Earth, the Moon and the Sun

• As the Earth moves in its yearly revolution
  around the sun, the moon moves in a monthly
  revolution around the Earth.At the same time both
  rotate.
• The motion of these three result in the changing
  appearance of the moon as seen from the Earth and
  the blocking of light.

20
Phases of the Moon

• The moon goes through all of its phases every
  29.5 days. The moon reflects sunlight toward the
  Earth.
• The moon has 8 phases.
• The moon is said to be waxing when the lighted
  area grows larger and waning when the lighted
  area appears to grow smaller.

21
New and Waxing Moon

• A new moon occurs when the moon comes between the
  sun and Earth and the side of the moon facing
  Earth is in darkness.One week later at First
  quarter moon, ½ of the moon appears lighted.
• Two weeks after the new moon, a full moon is
  visible and the Earth is between the moon and the
  sun.

22
Waning and New Moon

• The moon takes another two weeks to go through
  the waning-gibbous, last quarter and waning
  crescent phases.
• The moon then stars all over again as a new moon.

23
Solar Eclipse

• A solar eclipse occurs when the new moon comes
  directly between the sun and the Earth.
• The people in the umbra of the shadow see a total
  solar eclipse.
• The people in the penumbra, the larger outer
  shadow, see a partial solar eclipse.

24
Lunar Eclipse

• A lunar eclipse occurs when the moon passes
  through the Earths shadow.
• When the moon moves through the umbra, a total
  lunar eclipse occurs.
• When the moon moves through the penumbra, a
  partial lunar eclipse occurs.

25
Moon Earth

• As a result of the Earths gravitational pull on
  the moon, the side that faces Earth has a bulge.
• The moons gravitational pull on Earth results in
  the rise and fall of the oceans, known as the
  tides.

26
Tides

• The moons gravity causes the oceans to bulge in
  two places, the side facing the moon and the side
  facing away. This results in high tide.
• Low tides occur between the two bulges.
• There are two high tides and two low tides every
  24 hours.

27
Spring Tides

• During the full moon and the new moon phases, the
  high tides are higher than at other times. These
  are called spring tides.
• Spring tides occur because the sun and the moon
  are in a direct line with the Earth.

28
Neap Tides

• When the moon is at the first and last quarter
  phases, its gravitational pull on the oceans is
  partially cancelled by the suns gravitational
  pull. This results is lower high tides called
  neap tides.
• The varying distance between the Earth and moon
  due to the moons orbit also affects the tides. A
  perigee will cause extremely high tides.

29
The Space Age

• On October 4, 1957 Sputnik I was the first
  artificial satellite to orbit the Earth.
• Vanguard (Stayputnik), the United States first
  attempt was not successful.

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Artificial Satellites

• Communications
• Weather
• Navigation
• Scientific

31
Communication Satellites

• Communication satellites bean television
  programs, radio messages, and telephone
  conversations.
• The satellites receives a signal from a
  transmitting station on Earth and relays it to a
  receiving station in another location on Earth.
  They are often in geosynchronous orbit with the
  Earth.

32
Weather Satellites

• Weather satellites have made prediction more
  accurate.

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Navigation Satellites

• Navigation satellites can tell the exact position
  of ships, airplanes and cars within seconds.

34
Scientific Satellites

• The Explorer I, the first United States
  satellite, discovered the Van Allen radiation
  belt.
• The Infrared Astronomy Satellites (IRAS) found
  evidence of a black hole in the Milky Way galaxy
  as well as planetary systems forming around
  distant stars.
• The Upper Atmosphere Research Satellite (URAS)
  studies the ozone layer.

35
Laboratories in Space

• In 1973, the United States launched Skylab, and
  later Space Lab.
• In 1986, the Soviets launched Mir.
• Today we have the International Space Station.

36
Space Technology Spin-offs

• Heart pacemakers
• Lightweight tennis rackets
• Fabric that can withstand extreme temperatures
  and still be flexible
• Gel packs to draw excess heat away from humans
• Monitoring devices for vital statistics