Notes: The Earth, Moon, and Sun

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Notes The Earth, Moon, and Sun

• Chapter 12

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• Astronomy the study of the moon, stars, and
  other objects in space
• Earths axis the imaginary line that passes
  through the Earths center and the North and
  South poles
• Earth spinning on its axis is called its rotation

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• Earths rotation on its axis causes day and night
• It takes Earth about 24 hours to complete one
  rotation ? a day
• Revolution the movement of one object around
  another object
• The Earth revolves around the sun ? one
  revolution one year
• Orbit Earths path as it revolves around the
  sun (oval shape)

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Seasons on Earth

• Four seasons Winter, Spring, Summer, and Fall
• Sunlight directly hits the Earth at the equator,
  causing these areas to be the warmest
• The sunlight that hits the poles is spread out,
  resulting in cooler weather

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The Earths Seasons

• Summer Solstice For the Northern Hemisphere,
  Summer Solstice is the longest day of the year on
  June 21st.

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The Earths Seasons

• Winter Solstice is the shortest day of the year
  on December 21st.

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Winter Solstice Dec 21st
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The Earths Seasons

• Equinox Two days of the year half way between
  the solstice, the earths axis is neither
  pointed away or toward the sun. The daylight
  hours are equal to the nighttime hours.
• Vernal Equinox or Spring equinox is on March
  21st
• Autumnal Equinox is September 23rd.

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• Earth has seasons because its axis is tilted as
  it moves around the sun

The Moon
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Phases of the Moon

• The moon revolves around the Earth in the same
  amount of time it takes to rotate on its axis.
• Result ? The near side of the moon always faces
  Earth.

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• The different shapes of the moon you see from
  Earth are called phases.
• Phases are caused by changes in the relative
  positions of the moon, Earth, and the sun.
• The phases of the moon depends on how much of the
  sunlit side of the moon faces Earth.

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• When the moons shadow hits Earth or the Earths
  shadow hits the moon, an eclipse occurs.
• Solar eclipse when the moon passes between the
  Earth and the sun.
• Lunar eclipse when the Earth is directly
  between moon and sun during a full moon.

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Solar Eclipse
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Lunar Eclipse
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Solar Eclipse
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Tides
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What is a Tide

• The rhythmic rise and fall of the sea surface due
  to the moons gravitational pull.
• Every 12.5 Hours
• 6 hours rises
• 6 hours falling

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Use The Force

• The force of gravity pulls the moon and the earth
  toward each other.
• The closer 2 objects in space, the greater the
  gravitational pull.

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The moons gravity pulls on the earth at
different times and different parts of the earth
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Spring Tides Cause extra high tides because both
the moon and the sun are pulling on the
oceans. Neap tides Tides that are not very high
or low.
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Structure of the Moon

• The moon is ¼ the size of the earth.
• It has no atmosphere because it has very little
  gravity.
• The moons surface has craters, highlands and
  lowlands.

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• The moon has a partially molten-iron core, that
  is almost completely cooled.
• The moon has moon quakes which are similar to
  earth quakes, but theyre on the moon. )

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The Sun

• Chapter 14.2

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The Sun

• It makes up 99.8 of the solar systems mass.
• It holds all the planets in orbit due to its
  powerful gravitational pull.

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The Suns Interior

• The suns core produces its energy via nuclear
  fusion.

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The Core of the Sun

• Photosphere-The inner layer of the sun that
  produces light.
• Chromosphere- Middle layer that produces color
• Corona- The outermost layer of the sun

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The Core Continued

• Light and heat leaves the Suns surface and
  escapes into space, which provides the Earths
  energy.

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Solar Winds

• Electrically charged or magnetic particles that
  flow from the corona
• It takes 5 days for the solar wind to reach the
  earth

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• Particles reach speeds of 500km/s.
• They are mostly electrons protons.

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Sun Spots and Prominences

• Dark areas of cooler gases red loops of gas
  produced by magnetic fields.

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SOLAR FLARES

• Violent discharges of energy between two
  sunspots.
• This can knock out radio, T.V. telephone
  signals.

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Stars, Galaxies and the Universe (Chapter 15)
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Electromagnetic Radiation Energy that travels
through space in the form of waves.
Visible Light Light that you can see with your
own eyes.
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Electromagnetic Radiation
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Wavelength The distance from one crest of a wave
to another.

• Frequency The number of waves in an interval.

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Electromagnetic Spectrum ROYGBIV Red Orange Yello
w Green Blue Indigo Violet
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TOOLS OF ASTRONOMY
Spectrograph A tool that is used to obtain
information from stars by breaking up the colors
they emit.
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Chemical compositions Each element absorbs
different wavelengths of light and shows up as
lines on a spectrum.
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Temperature Stars at different temperatures
produce different line spectra.
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Characteristics of stars

• GALAXY A huge mass of stars, gas and dust held
  together by gravity. We live in the Milky Way
  Galaxy.

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Distances to stars

• Light Speed Light travels at 300,000 km/s.

• Light Year The distance light travels in a year.

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