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Analemma by Shadow
Name: Nolen
Status: student
Grade: 9-12
Location: SC
Country: USA
Date: Winter 2011-2912
Question:
Assume that you had a room which has only one window, to the south. Further, assume that this window is covered with only a small opening, about one inch in diameter, allowing sunlight. Further, assume that, on January 1 of a particular year, one marked, on the floor of the room, the spot where the ray of light from the sun, through the opening, struck the floor. Further, assume that one does this at the same time on the first day of each month during the year. Question: Would the twelve marks on the floor go strictly up and down, or would they resemble a figure "8"? Or some other figures?
Replies:
You would get a slender but distorted figure 8, which would be
slightly off 'upright'.
Howard Barnes
Astronomer.
Dear Nolen,
I am not sure about the geometry of the analemma, but it does appear
as a type of figure 8 which is the path the Sun apparently takes during its
yearlong journey around the sky!
Sincerely
David H. Levy
Nolen,
I suggest you watch at least the first 7 or so minutes of this video:
http://www.youtube.com/user/sixtysymbols?feature=g-all-u#p/search/3/s_NN8pZxTP8
- it provides a computer-generated visualization of the Sun's motion. There is even a section of the video where the motion of the Sun over a period of a year at the same time of day each year is shown. The short answer is that it would depend on the time of day you chose, and what latitude you were at.
Greg (Roberto Gregorius)
Canisius College
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Update: June 2012
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