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Re: [Phys-l] celestial motion



The apparent motion of the sun across the sky is 15 degrees per hour (Earth rotates 360 degrees per day, give or take depending on sidereal versus solar day). The sun has an angular size of approximately 0.5 degrees. That's about 30 solar diameters per hour, which works out to 4 per 8 minutes. Why does that seem too large? That's only 2 degrees of arc.

Bill Nettles
Union University
Jackson, TN

"LaMontagne, Bob" <RLAMONT@providence.edu> 8/23/2008 4:27 pm >>>
The sun moves approximately 1 degree / day through the sky.

Bob at PC

________________________________

From: phys-l-bounces@carnot.physics.buffalo.edu on behalf of Anthony Lapinski
Sent: Fri 8/22/2008 1:26 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] celestial motion



Thanks for all the interesting/detailed responses so far. I simply wanted
to know the Sun's approximate angular speed across the sky. How many of
its own diameters does it move in 8 minutes. I read somewhere years ago
that it was two diameters, but my calculations showed four, which seemed
too large.