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Name: Heather S.
Status: educator
Grade: 6-8
Location: WA
Country: N/A
Date: 7/29/2005


Question:
Why does the real time of local noon seem to change from one month to the next?


Replies:
This is because the Earth's orbit around the Sun is not circular. The Sun-Earth distance varies from approximately 146 million to 153 million km (91 million to 95 million miles), so the apparent Sun is early each November and late each February. A further complication is the tilt of the Earth's axis 23.5 from the orbital plane.

The maximum divergence is 14m 14s in February, and 16m 26s in November, with secondary 'peaks' of 3m 41s in May and 6m 29s in July.

Howard Barnes.
Astronomer.



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