Earth and Moon in Space

1
Earth and Moon in Space
2
Earth Moves

• Earth moves in space
• Earth spins around an imaginary line called an
  axis
• The axis is an imaginary line passing through the
  poles and the center of the Earth

3
Rotation

• Rotation is the spinning of the Earth on its
  imaginary axis
• Earth makes one complete rotation every 24 hours
• Rotation of the Earth causes day and night as a
  point on the Earth rotates toward or away from
  the sun

4
Revolution

• Earth moves around the sun in a regular, curved
  path called an orbit
• Revolution is the movement of Earth in an orbit
  around the sun
• Earth takes 365¼ days to make one revolution
  around the sun (one year)
• Earth rotates on its axis and revolves around the
  sun at the same time

5
Seasons

• Seasons are caused by the tilt of the Earth on
  its axis.
• The hemisphere of the Earth that is tilted toward
  the sun receives more of the suns heat and light
  and its temperatures are warmer.
• Summer happens in a hemisphere when the
  hemisphere is tilted toward the sun.

6
Seasons

• Winter happens when a hemisphere is tilted away
  from the sun.
• When a hemisphere is tilted away from the sun, it
  receives less heat and light and the Earths
  temperatures are cooler.

7
Seasons
8
Solstice

• Solstice is point at which the sun reaches its
  greatest distance north or south of the equator.
• In the northern hemisphere, the winter solstice
  happens around December 21 or 22.
• The winter solstice has the fewest daytime hours.

9
Solstice

• In the northern hemisphere, the summer solstice
  happens around June 21 or 22.
• The summer solstice has the most daytime hours.

10
Equinox

• When the sun reaches an equinox, it is directly
  above the Earths equator.
• At the equinox, the number of daytime and
  nighttime hours equal each other all over the
  world.
• In the northern hemisphere, the spring equinox is
  March 20 or 21 and the fall equinox is September
  22 or 23.

11
The Moon

• It's Just a Phase It's Going Through...

12
Moon

• Our planet's large natural satellite, the Moon,
  is the easiest astronomical object to observe.
• The only "scientific instrument" you'll need at
  first is a pair of eyes.

Picture from NASA
13
The Moon's Orbit

• Rotation
• Moon is spinning on its axis, once every 27.3
  days
• Revolution
• The moon orbits around the Earth
• Moon revolves around the Earth once every 27.3
  days

14
Why do we never see the DARK SIDE?

• Synchronous Rotation is the reason we never see
  the dark side of the moon.
• Over the millennia, the Moon has become "locked"
  into a special kind of motion around the Earth.
• It rotates on its axis at the same pace as it
  revolves around the Earth
• As a result, the Moon keeps the same face toward
  us throughout its orbit.

15
Phases

• The lighted side of the moon always faces
• the sun.

16
New Moon
What we see

• New moon occurs when the moon is between the sun
  the Earth.
• The dark side of the moon is facing the Earth.

What is happening from above.
Sunlight
17
Full Moon
What we see

• The full moon occurs when the Moon the Sun are
  on opposite sides of the Earth.
• The lighted side of the moon is facing Earth.

What is happening from above.
Sunlight
18
Blue Moon

• When there is more than one full moon in a month,
  the second moon is called a blue moon.
• A blue moon happens every two years on average.
• The phrase, Once in a blue moon means very
  rarely or very seldom or almost never.

19
First QuarterMoon
What we see

• The First quarter moon occurs when the moon is
  halfway between new and full.
• As seen from the Earth, half the moons disk is
  illuminated.

What is happening from above.
Sunlight
20
Third QuarterMoon
What we see

• The Third or last quarter moon occurs halfway
  between the full moon the new moon.
• As seen from the Earth, half the moons disk is
  illuminated.

What is happening from above.
Sunlight
21
Waxing

• When the moon is between new full, the visible
  part of the moon is increasing.
• This is called waxing

Sunlight
22
Waning

• When the moon is between full new, the visible
  part of the moon is decreasing.
• This is called waning.

Sunlight
23
Crescent Moon
Full Moon

• When the moon is between New 1st Quarter it is
  called a waxing crescent.

1st Quarter
3rd Quarter
Waning Crescent

• When the moon is between 3rd New it is called
  a waning crescent.

Waxing Crescent
New Moon
Sunlight
24
Gibbous Moon
Full Moon
Waning Gibbous

• When the moon is between 1st Quarter Full it is
  called a waxing gibbous.

Waning Gibbous
1st Quarter
3rd Quarter

• When the moon is between Full 3rd it is called
  a waning gibbous.

Waning Crescent
Waxing Crescent
New Moon
Sunlight
25
Moon Movie
26

• Link to current phase of the moon
• http//tycho.usno.navy.mil/vphase.html
• Link to moon phases pictures and lunation movie
• http//aa.usno.navy.mil/faq/docs/moon_phases.php

27
Forces governing planetary motion

• Sun and planets or
• Earth and moon

28
Force

• A force is a push or pull one body exerts on
  another
• A force causes an object to accelerate in the
  direction of the force

29
Inertia

• Tendency of an object to resist any change in
  motion
• A moving object stays moving

30
Inertia

• An object that is not moving will stay still,
  unless a force acts on it
• An object at rest stays at rest

31
Inertia

• A sliding hockey puck moves at the same speed and
  direction until it hits a wall or a stick
• Velocity is constant, no acceleration

32
Inertia

• If a force (a moving hockey stick or the wall)
  acts on the puck, then it will change direction
• Velocity changes

33
Mass and Inertia

• More mass an object has, the more inertia it has
• More mass, harder to change the motion

34
Newtons First Law

• An object moving at a constant velocity keeps
  moving at that velocity unless a net force acts
  on it.

35
Newtons First Law

• An object at rest, stays at rest unless a net
  force acts on it.

36
Newtons First Law

• Newtons first law is sometimes called the Law of
  inertia

37
1st Law

• Unless acted upon by an unbalanced force, this
  golf ball would sit on the tee forever.

38
1st Law

• Once airborne, unless acted on by an unbalanced
  force (gravity and air fluid friction), it
  would never stop!

39
Friction

• Why then, do we observe every day objects in
  motion slowing down and becoming motionless
  seemingly without an outside force?
• Its a force we sometimes cannot see friction.

40

• Objects on earth, unlike the frictionless space
  the moon travels through, are under the influence
  of friction.

41
Newtons 1st Law and You
Dont let this be you. Wear seat belts. Because
of inertia, objects (including you) resist
changes in their motion. When the car going 80
km/hour is stopped by the brick wall, your body
keeps moving at 80 km/hour.
42
Gravity
43
Gravity

• Force exerted by every object in the universe on
  every other object in the universe.

44
Force of Gravity

• Gravity is affected by mass and distance
• Closer things exert more gravity on each other
• Object with more mass exerts more gravity on an
  object of less mass

45
Gravity is a pulling force
It pulls things down towards the earth
46
Things fall because of gravity
47
Things always fall down
48
Gravity was discovered by a scientist called
Isaac Newton
49
Stories say he discovered Gravity when an apple
fell on his head
50
Gravity holds everything and everyone on the earth
Even in Australia
51
In Space, Gravity keeps the planets moving around
the sun
52
2nd Law
F m x a
53
2nd Law

• The net force of an object is equal to the
  product of its mass and acceleration, or Fma.

54
Circular motion

• Circular motion (planetary motion) occurs because
  of two things.
• 1. An object, like a planet or the moon, is
  already moving with a certain speed in a
  particular direction
• 2. A force (gravity) acts on the object.

55

• Gravity causes Earth to speed up (accelerate) in
  a straight line towards the Sun
• Newtons second law explains this effect - a net
  force causes an object with mass to accelerate

56

• If Earth was not moving to begin with, the force
  of gravity would cause the Earth to accelerate
  until it collided with the Sun

57

• Combination of Earths linear motion and the
  acceleration toward the Sun (sideways to the
  linear motion) leads to a curved path, orbit,
  around the Sun

58
Earth travels in an orbit around the Sun because
of two forces
59
Moon travels in an orbit around Earth for the
same reasons
60

• If gravity stopped working, then Earth would move
  in a straight line at a constant rate

61

• If there was no linear motion, then the Earth
  would fall into the Sun

62
Projectiles

• Projectiles anything thrown or shot through the
  air
• Projectiles have horizontal and vertical
  velocities and travel in a curved path

63
Projectiles

• Horizontal velocity is constant due to inertia
• Vertical velocity increases due to gravity
• Gravity exerts an unbalanced force and pulls the
  object down

64
(No Transcript)
65
Artificial satellites

• If a projectile moves with enough linear speed so
  that its fall towards the ground exactly matches
  the curvature of the Earth, then the projectile
  will orbit the Earth