EARTH, MOON

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EARTH, MOON SUN

• Unit 10

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Section 1 The Earth in Space

• What do we call the study of the moon, stars, and
  other objects in space?

• Astronomy

• Astronomers- scientists who study astronomy

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• Ancient astronomers studied the sun moon as
  they appeared to travel across the sky.
• They thought the Earth was standing still!

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Does the Earth move?

• YES!!
• How??

• Two ways
• Rotation
• Revolution

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Why does the sun Rise Set?

• Rotation of the Earth
• The Earth spins on its Axis

• One full rotation takes 24 hours

• Day and night is determined by the direction the
  Earth is facing.

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How else does the Earth move?

• REVOLUTION
• Earth travels around the sun
• The path it follows is called its ORBIT
• One complete revolution around the sun is called
  a year

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The Calendar

• Egyptians were among the first Astronomers.
• Counted days between the appearance of the star
  Sirius, to predict annual floods.
• Observed 365 days between each siting.

February
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Whats Leap Year all about?

• Scientists concluded that it actually takes the
  Earth 365.25 days to revolved around the Sun.
• For 3 years we have 365 days
• Every 4th year we have 366 days
• Leap Year add Feb. 29th

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What would happen if we didnt have Leap Year?

• If we counted every single year as having exactly
  365 days, then..
• As years pass, the seasons would shift
• For example, spring would start sooner each year.
  

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Months

• Developed in order to divide the year into
  smaller portions.
• Early calendars Counted the days between one
  full moon to the next- 29 ½ days
• Todays Calendars 11 months with 30 or 31 days,
  and one (February) with 28 or 29

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SEASONS

• Why is it colder near the North South poles,
  but not the Equator?
• Temperature depends on the angle that Sunlight
  hits the Earth.
• See Figure 2, pg 18
• What part of the Earth gets the most direct
  sunlight? The least?
• Equator Poles

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What causes the Seasons?

• Tilt of the Earths Axis
• 23.5 degrees
• As Earth revolves, one Hemisphere is tilted
  toward the sun, while the other is tilted away

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Hemispheres

• When our Northern Hemisphere is tilted toward the
  sun, we have summer, while the Southern
  Hemisphere has winter, and vice versa!

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What if the Earth was not tilted on an Axis?

• Temperatures would remain constant all year
• There would be no seasons!

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Solstice

• 2 days of the year when the noon Sun is directly
  above 23.5 degrees north, or south latitude
• The shortest longest days of the year
• Whats latitude?
• Measured distance north or south of the equator

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Summer Solstice

• Longest day of the year
• (longest period of daylight)
• 1st day of summer
• June 21 in the Northern Hemisphere
• December 21 in the Southern Hemisphere

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Winter Solstice

• Shortest day of the year
• (shortest period of daylight)
• 1st day of winter
• December 21 in Northern Hemisphere
• June 21 in Southern Hemisphere

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Equinox

• Half way between solstices
• 2 days per year
• neither hemisphere is tilted toward or away from
  the sun
• Noon sun is directly over Equator
• Equal lengths of daytime and nighttime

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• Spring Equinox
• 1st day of spring
• March 21 in Northern Hemisphere
• September 21 in Southern Hemisphere
• Fall Equinox
• 1st day of fall
• September 21 in Northern Hemisphere
• March 21 in Southern Hemisphere

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How do the changing seasons affect living things?

• Warmer days allow for plants to grow
• Animals can get more food
• Colder days cause plants to stop growing
• Many animals hibernate or migrate

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SECTION 2 PHASES ECLIPSES
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The Moon

• Earths closest neighbor
• Revolves around the Earth
• Rotates on an axis
• About 384,000 km from Earth
• If you drove 100 km per hour straight to the
  moon, it would take you 5 months to get there!

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Motions of the Moon

• Rotation and Revolution both take about 27.3 days
• A moon day and a year are the same
• Orbit is an ellipse (oval) shape
• The same side of the moon always faces us
• The Near Side
• The Far Side always faces away

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Phases of the Moon

• Why does the moon shine?
• Does not produce its own light
• Reflects light from the sun
• What causes the phases?
• They depend on how much of the sunlit side of the
  moon faces Earth

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First Quarter
Waxing Gibbous
Waxing Crescent
New Moon
Full Moon
Waning Crescent
Waning Gibbous
Third Quarter
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Why do we see different shapes of the moon?

• Only one half of the moon is sunlit
• Since it is always revolving around the Earth, we
  see it from different angles during the month

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The Cycle of Phases

• The time it takes for the moon to go from a New
  Moon to a Full Moon is about 29.5 days.
• Remember
• Phase Cycle 29.5 days
• Revolution/Rotation 27.3 days

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Eclipses

• The moons orbit is on a tilt, so it usually does
  not go directly between the Earth and Sun
• Sometimes, the moon comes between the Earth and
  Sun, or the Earth comes between the Sun and Moon
• This casts a shadow on either Earth or the moon,
  called an Eclipse

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Solar Eclipse

• When the moon passes between the Earth and the
  Sun
• Blocks sunlight from reaching the Earth
• Moons shadow is cast on the Earth
• New Moon phase

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Solar Eclipse
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• Two parts to Moons shadow
• Umbra Penumbra
• Total Solar Eclipse Umbra
• Darkest part of shadow
• Totally blocks sun
• Only a small area on Earth can view it
• Partial Solar Eclipse Penumbra
• Less dark, larger part of shadow
• Part of the sun is visible
• Casts a larger shadow on Earth, making the sky
  dark

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Lunar Eclipse

• Earth is directly between moon Sun
• Earth blocks sunlight onto moon
• Moon is in Earths shadow
• Full Moon

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Partial Lunar Eclipse

• Moon passes only partly through the Earths umbra
• Can watch it pass by for hours

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Total Lunar Eclipse

• When the entire umbra casts a shadow on the Moon
• Can be seen anywhere moon is visible

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Section 4 Earths Moon
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Structure Origin of the Moon

• 3,478 km in diameter
• (about the distance across U.S.A.)
• About ¼ the Earths diameter
• Mass is about 1/80 of the Earth
• Density is about the same as Earths outer layers

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How did the Moon form?

• Many possible hypotheses
• Did the moon come from somewhere else in the
  solar system and get caught by the Earths
  gravitational pull?
• Did the Earth spin so fast that it threw material
  off that clumped together?
• Collision Theory

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The Collision Theory

• 4.5 billion years ago
• Another object collided with Earth
• Material from Earths outer layers was thrown out
  to space, clumping together to form the moon

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Looking at the Moon from Earth

• 1609 Galileo invented the Telescope
• Observed the moons surface
• Identified 3 distinct features craters, maria
  and highlands

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• Craters
• Round pits caused by the collision of meteoroids
• Maria
• Latin for seas
• Dark, flat areas
• They are not oceans
• Were once flooded with molten material billions
  of years ago
• Highlands
• Mountains

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Moon Rocks Moonquakes

• Astronauts study moon rocks to learn about the
  moon
• Most rocks they found were made from cooled
  molten material
• The moon was very hot at one time
• Many rocks were broken, suggesting many meteoroid
  collisions

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• Measuring Equipment
• To study the moons interior
• Measured heat flowing from interior
• Moon has almost cooled completely since formation
• Seismometer measures earthquakes
• Detected weak moonquakes
• Changes in moons interior