Earth%20in%20Space

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Earth in Space

• Chapter 7, Section 1

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Earths size and shape

• Earth is a sphere
• How do we know?
• No matter where you are on Earth, gravity causes
  all objects fall toward the center of Earth
• If you are on a ship approaching a land mass, you
  see the tops of the tallest buildings first and
  the ground level last.

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Other fun Earth facts

• Diameter 12,756 Km
• Circumference 40,075 Km
• Mass 598,000,000,000,000,000,000,000 Kg
• Avg. Distance to Sun 149,600,000 Km
• Avg. Distance to Moon 384,400 Km
• Period of rotation 23hr, 56 min, 4 sec (sidereal
  day)
• Rotation 24 hr 4 sec (solar day)
• Period of revolution 365 ¼ days

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Earths magnetic field

• The outer core of the Earth spins at a different
  speed than the outer layers this causes a
  magnetic field with North and South magnetic
  poles
• The magnetic poles are not static and move
  periodically since Earth rotates!
• The magnetic poles deflect the solar wind, a
  stream of harmful electromagnetic particles
  ejected by the Sun.

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The magnetic poles
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Earth as a magnet
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Magnetic poles deflecting the solar wind
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Earths magnetic field

• Some of these E.M. particles are pulled into the
  Earths magnetic poles
• When this occurs, their energy can cause the
  particles in the atmosphere to glow
• This phenomenon is called the Aurora Borealis (or
  Aurora Australis in the Southern Hemisphere)

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Aurora
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Earth orbits the Sun

• Just like the orbits of all of the planets,
  moons, and comets, the Earths orbit is an
  ellipse.
• Of the three other terrestrial (rocky surface)
  planets, Venuss atmosphere is the most like
  Earth, but conditions on Mars are most like Earth
  
• Venus is considered to be Earths twin due to its
  size!

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Time and Seasons

• Chapter 7, Section 2

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Measuring time on Earth

• The Earth makes one rotation in apx. 24 hours.
• This spinning causes the Sun to appear to move
  across the sky from east to west.
• If the Earth spins 360 every 24 hours then it
  spins 15 every hour (hence time zones).
• Time zones are modified to fit cities, regions,
  or even countries.

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Time Zones
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• The International Date Line is located at 180
  longitude (in the middle of the Pacific)
• The Earth makes one revolution around the Sun
  every 365.25 days
• The Earths orbit around the Sun is in an ellipse
  (an elongated circular path)

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Why do seasons change?

• The seasons are not caused by how close we are to
  the Sun!!!!
• The seasons are caused by the axis, or tilt, of
  the Earth on its axis
• The tilt of the axis is 23.5
• During our summer, the Northern Hemisphere gets
  more direct sunlight and more hours of it than
  the Southern Hemisphere does.
• During our winter, the Northern Hemisphere gets
  less direct sunlight and less hours of it than
  the Southern Hemisphere does.

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Intensity during the year
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The Suns intensity varies on your latitude
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Length of Day
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• At only two times during the year, all places on
  Earth have 12 hours of daylight and 12 hours of
  darkness.
• They are called the equinox and occur on apx.
  March 21st and September 22nd.
• On apx. June 21st, the summer solstice occurs.
  It is the day with the most hours of sunlight in
  the Northern Hemisphere and the day with the
  least hours of sunlight in the Southern
  Hemisphere.
• On this day, the sun can be seen directly
  overhead at the Tropic of Cancer.

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• The opposite of the summer solstice is the winter
  solstice. It is the day with the most hours of
  sunlight in the Southern Hemisphere and the day
  with the least hours of sunlight in the Northern
  Hemisphere.
• On this day, the sun can be seen directly
  overhead at the Tropic of Capricorn.

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Earths Moon

• Chapter 7, Section 3

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Movement of the Moon

• The Moon revolves around the Earth every 27.3
  days.
• The Moon rotates (27.3 days) at the same speed
  that it revolves! So, the same side of the Moon
  always faces the Earth.
• How Does the Moon affect gravity?
• All objects that have mass have gravity. The
  Moons gravity also pulls on the Earth and all
  objects on Earth, causing ocean tides. The suns
  gravity also pulls on the tides too!

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Moonlight

• The Moon shines because it reflects sunlight off
  of its surface
• Just like half of the Earth experiences day while
  the other half is night, so does the Moon.
• Moon phases are the changing appearances of the
  Moon as seen from Earth. The phase you see
  depends on the relative positions of the Sun,
  Earth, and Moon.

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Random Moon Phase Facts

• It takes the moon 29.5 days to complete the
  phases.
• Two full moons in one calendar month is called a
  blue moon.
• Technically, each moon phase only lasts an
  instant..but to our eyes, it looks the same for
  3 ½ days!
• Waxing phase right side is reflecting light and
  continues to reflect more each night.
• Waning phase left side is reflecting light and
  reflects less light each night.

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Eclipses

• There are two types of eclipses
• Solar eclipse when the Moon casts a shadow onto
  the Earth
• Lunar eclipse when the Earth casts a shadow
  onto the Moon
• Eclipse terms
• Umbra- where the sunlight is totally blocked
• Penumbra where the sun is partially blocked

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Upcoming Lunar Eclipses

• 2012 Nov 28Penumbral-0.187-Europe, e Africa,
  Asia, Aus., Pacific, N.A.
• 2013 Apr 25Partial0.01500h27mEurope, Africa,
  Asia, Aus.
• 2013 May 25Penumbral-0.934-Americas, Africa
• 2013 Oct 18Penumbral-0.272-Americas, Europe,
  Africa, Asia
• 2014 Apr 15Total1.29103h35m01h18mAus., Pacific,
  Americas
• 2014 Oct 08Total1.16603h20m00h59mAsia, Aus.,
  Pacific, Americas
• 2015 Apr 04Total1.00103h29m00h05mAsia, Aus.,
  Pacific, Americas

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The Moons Surface

• The moon has no atmosphere to burn up meteors and
  no weather to cover up scars left by meteors.
• When the Moon was still cooling, meteors slammed
  into the Moon and broke through the crust causing
  lava to fill the craters causing dark-colored
  flat regions known as Maria.
• Impacts on the Moon throughout its history caused
  a layer of rock and dust on its surface known as
  regolith.

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Life in the Solar System (skip this section)
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• Lunar
• Crater

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Far Side of the Moon
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The Moons interior

• The Moon has a very thick Mantle and a small
  liquid iron core.
• Exploring the Moon
• In the 1960s, the U.S. Apollo Missions sent 24
  astronauts to the Moon with 12 of them walking on
  its surface.
• In the 1970s, the U.S. Clementine spacecraft
  orbited the Moon taking pictures to map the
  surface.
• In 1998, the U.S. Lunar Prospector spacecraft
  took even more detailed images of the surface of
  the Moon.

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Origin of the Moon

• The generally accepted theory of how the Moon was
  formed is called the Giant Impact Theory.
• The G.I.T. states that while the Earth was still
  cooling, a Mars-sized asteroid slammed into Earth
  causing a wad of material to eject out the other
  side of Earth. This material reformed into what
  is now the Moon.
• The G.I.T. also explains how the Earth got its
  iron core and water.

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Lets Review!

• Pick up your clicker and turn it on.

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A lunar eclipse occurs when the Earths umbra
blocks the moon.

1. True
2. False

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A solar eclipse occurs during a new moon phase.

1. True
2. False

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Regolith on the moon are the dark, flat regions
made of dried lava beds.

1. True
2. False

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Many meteors were able to strike the moons
surface since it does not have an atmosphere.

1. True
2. False

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If you are in the penumbra during a solar
eclipse, all of the sun will be blocked my the
moon (total eclipse).

1. True
2. False

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The Giant Impact Theory explains how the solar
system was formed.

1. True
2. False

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A partial eclipse occurs when you are in the
objects umbra.

1. True
2. False