Astronomy Questions

The following are questions submitted by people using the Tycho System. All questions will be read and hopefully answered twice a week.
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Question # 0 from :
slicing.science.gmu.edu @ Wed Sep 14 15:36:47 1994


Question # 1 from : chochste@science chochste@science
tracing.science.gmu.edu @ Mon Sep 19 13:51:39 1994

Explain Keplar's law of planetary motion, ( if you increase the orbital radius of Earth to 2 AU's , the orbital period would be ?) I do not know how to do this


Question # 2 from : jwallin@gmu.edu
galileo.gmu.edu @ Tue Sep 20 17:46:46 1994

Kepler's Laws basically describe how planets move. The third law is a relationship between the orbital distance and the orbital period. The equation is Period^2 = (semi-major axis)^3. This means that if you have a planet with an orbital radius of 2 AU, Period^2 = (2)^3. So, Period^2 = 8. If you take the square root of both sides, you find that the period is the square root of 8 years. The square root of 8 is about 2.8, so the orbital period is about 2.8 years. Hope this helped. jw