Naked Eye Observations of the Nighttime Sky

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Naked Eye Observationsof the Nighttime Sky
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Always different stars

• Different stars are overhead at different times
  of night. Imagine a constellation that is to the
  east a couple of hours before midnight, overhead
  at midnight, then in the west a few hours after
  that.
• With your group, describe how this is possible,
  including a sketch.

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Zenith and Horizon
http//cse.ssl.berkeley.edu/IU/ISTAT/astross/activ
ities/andromeda.html
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Angular measure
Bennett, Donahue, Schneider, and Voit, The Cosmic
Perspective
Freed,am and Kaufmann, Universe
Freed,am and Kaufmann, Universe
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The celestial sphere
Bennett, Donahue, Schneider, and Voit, The Cosmic
Perspective
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Results of the rotation of Earth
Bennett, Donahue, Schneider, and Voit, The Cosmic
Perspective
Bennett, Donahue, Schneider, and Voit, The Cosmic
Perspective
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Results of the rotation of Earth
MasteringAstronomy
http//www.davidmalin.com/miller/source/dm1-17_72.
html
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Seen from a different latitude
http//www.davidmalin.com/miller/source/dm1-16_72.
html
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Looking in the other direction
http//www.davidmalin.com/miller/source/dm1-17_72.
html
http//physics1.howard.edu/School/astro/notes.htm
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Always different stars

• Different stars are overhead at different times
  of the year. Imagine a constellation that is to
  the east in late fall, overhead during
  mid-winter, then in the west in early spring.
• With your group, describe how this is possible,
  including a sketch.

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Revolution of the Earth around the Sun
MasteringAstronomy
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The Ecliptic
Freed,am and Kaufmann, Universe
http//singingsun.com/
Kuhn, In Quest of the Universe
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Seasons

• Northerners have cold days in January because
• a. the Earth is farthest from the Sun in
  January.
• b. the orbital velocity of the Earth is largest
  in January.
• c. the Sun is lower in the sky in January.
• d. El Niño is always strong in January.
• WHY is the Sun lower in the sky in
• January than in July (in the northern
• hemisphere)?

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The Earths tilt
Freed,am and Kaufmann, Universe
Kuhn, In Quest of the Universe

• Interactive Reason for the Seasons

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The Analemma
http//www.sundials.org/links/local/pages/dicicco.
htm
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Precession
MasteringAstronomy
http//oceanworld.tamu.edu/students/iceage/iceage2
.htm
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Planets over Stonehenge
http//antwrp.gsfc.nasa.gov/apod/ap020509.html
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The plane of the Solar System
Chaisson and McMillan, Astronomy Today
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Mercury
http//astro.unl.edu/naap/ssm/elongation.html
http//www.cuyastro.org/gallery_planetary.html
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Venus
Sunrise
Sunset
http//backyardmoon.pwp.blueyonder.co.uk/1027.htm
Sanibel Island, FL, 8/9/06
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Venus
http//astro.unl.edu/naap/ssm/elongation.html
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Jupiter and Saturn
http//apod.nasa.gov/apod/ap010322.html
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Motions of the planets
http//www.davidcolarusso.com/astro/
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Mars
http//antwrp.gsfc.nasa.gov/apod/ap060422.html
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Mars retrograde motion
http//antwrp.gsfc.nasa.gov/apod/ap031216.html
MasteringAstronomy
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Necessary Terminology

• Explain the following terms, preferably with a
  sketch
• Zenith and Horizon
• Celestial sphere
• North and south celestial poles
• Celestial equator
• Circumpolar
• Rotation and Revolution
• Ecliptic
• Solstices (summer and winter)
• Equinoxes (vernal and autumnal)

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Guiding Questions

• Explain how the rotation of the Earth produces
  the change of positions of the stars over the
  course of a night.
• Explain how ones location on the Earth affects
  how the stars appear to move.
• Explain how the revolution of the Earth around
  the Sun produces the change of constellations
  over the course of a year.
• Explain how the tilt of the Earth produces the
  seasons.

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Guiding Questions

• Explain what observations of the planets indicate
  that the solar system is in a plane.
• Explain how observations of the planets indicate
  that the planets orbit around the Sun, Mercury
  and Venus close to the Sun, and Mars, Jupiter and
  Saturn farther away.
• Discuss what planets are currently visible in the
  nighttime sky as well as where and when to find
  them.

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Sample Questions

• Explain why the Earth and Mars have seasons while
  Jupiter does not.
• Would you ever observe planets near the Big
  Dipper or Orion? Explain why or why not.
• Explain (including a sketch) why you see
  different stars in the sky just after sunset and
  just before sunrise.
• Explain (including a sketch) why you see
  different stars at midnight during the winter
  than you do at midnight during the summer.