(From the lesson on Motions of the Earth)
Directions: All answers must be word processed! Reference any figures or quotes used from other sources.
(1 points)
1. Describe deflection of the vertical and how it affects observations made by
surveyors?
(1 points)
2. Explain how the ionosphere affects GPS signal propagation.
(1 points)
3. Describe the external sources that affect
precession and nutation of the Earth's spin axis? What physical phenomena causes
these motions?
(1 point)
4. Explain why the sun doesn't set in the Artic Circle during the summer. Draw a
sketch that demonstrates this phenomenon.
(1 points)
5. In your own words, describe why the solar day is longer than the sidereal
day. Use a sketch.
(2 points)
7. Find the x and y coordinates of the instantaneous spin axis
for August 8, 2006 on the IERS web site. (Note: They are there, search and
find!)
(1 point)
8. Using software (e.g. Excel or Mathcad) and data from the
IERS web site, create a polar plot of the Earth's mean pole position (x,
y) from 1900.0 to 2006.0.
(1 point)
9. In your own words, describe the method used by Eratosthenes to determine
the radius of a spherical Earth. Can this method be duplicated today?
Last Updated:
September 14, 2006
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