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The Sun


Distance: 147-152 million km.
Diameter: 1.4 million km.
Apparent cross-section: About 0.53 degrees.

Notes: Strictly speaking of course, the sun does not orbit the earth. As explained by James Miller (see below), the Sun's position can be computed as if it did. A sample Keplerian Element file is included with the program if you would like to experiment. However, WinOrbit predicts the Sun's position using a trigonometric series expansion (sine and cosine terms) such as that published in the Astronomical Almanac. Note that the Sunrise and Sunset times (AOS/LOS) published in the Astronomical Almanac, World Almanac, and other tabulations, assume a particular atmospheric refraction, and allow for the width of the solar disk, so that the edge of the sun is visible when the center is still about 0.8 degree below a level horizon. WinOrbit makes no such assumption and reports the "true" position of the center of the sun's disk. The distance reported is to the center, likewise ignoring the substantial radius of the sun.

Tracking the Sun with WinOrbit: The sun and moon will be found in the Tracking list in the Main Window ahead of any satellite maps. They are also found in the Satellite Selection list in the Print Dialog Box.

References:
"Keplerian Elements for the Sun", James Miller, G3RUH, Amateur Satellite Report, no. 137, December 1, 1986, p. 4.
"Pathfinder: Improved Minimuf Program", Ron Todd, K3FR , ham radio, May 1988, p. 26; and October 1988, p. 47.
"World Almanac and Book of Facts 1995", Funk and Wagnalls, Mahwah, NJ, 1994, p. 267-285.
"Astronomical Almanac for the Year 1994", US Government Printing Office, Washington, 1993, p. C24. (A new edition is published each year).

Satellite List

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