Astronomy/Distance from sun

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Expert: Jayendra Upadhye - 5/19/2005


Question
Why does Mercury's distance from the sun differ  

Answer
Hi Mark,
There are 2 aspects to that.
1 - Mercury has an elliptical orbit. It's orbit is 12 times more eccentric than the earth.
ref:- http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html
which is a very good comparison page.

2 - At perihelion something happens to its orbit that makes the direction of its semimajor axis, "precess".
This "something" has a lot to do with einsteinian warping of space due to sun's gravity.
Indeed this precession had been predicted by einstein and was later confirmed by astronomers, to be the reason of mercury's strange behaviour.
refer to this one of many sites on the subject, obtained by typing "orbital precession mercury" into google's search pane.
http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node98.html
Hope that suffices.
Jayen

Astronomy

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Jayendra Upadhye

Expertise

1 - General questions on most astronomy topics such as:- Solar system, Cosmology, Black holes, Quasars, Dark matter etc. 2 - General questions about the geologies of planets. 3 - General questions about Orbits and laws governing them. 4 - General questions about rockets / spaceships 5 - General questions about stellar interiors and supernovas.

Experience

I was an askme.com expert rated no#1 for quite some time - and was top ten there by the time it closed - in Astronomy and general science categories.

Education/Credentials
Bachelor of Engg. (Electrical engg), Maharaja Sayajirao university of Baroda, Gujarat, India.

Awards and Honors
None to write about except the askme rating if it is any worth!

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