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== Orbital oddities ==

== Orbital oddities ==

It was the study of this planet's orbit that [[Albert Einstein]] used to help confirm the theory of General Relativity.<ref>Testing general relativity [http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31277 European Space Agency] Accessed July 16 2007</ref><ref>Albert Einstein [http://www.phy.hr/ Fizički odsjek] Accessed July 16 2007</ref>

It was the study of this planet's orbit that [[Albert Einstein]] used to help confirm the [[General Theory of Relativity]].<ref>Testing general relativity [http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31277 European Space Agency] Accessed July 16 2007</ref><ref>Albert Einstein [http://www.phy.hr/ Fizički odsjek] Accessed July 16 2007</ref> Specifically, Mercury's [[apsis|perihelion]] precesses by 43 arc-seconds per century, or more than [[Sir Isaac Newton|Newtonian]] physics alone would predict from the respective masses of Mercury, the Sun, and the other planets. Astronomers of the period hypthesized either an [[Asteroid Belt|asteroid belt]] or another planet (which they named [[Vulcan (planet)|Vulcan]]) inside Mercury's orbit. Einstein's second-order correction to Mercury's orbit accounted exactly for the 43 arc-seconds of precession and obviated the need to look for any unseen asteroids or innermost planet.<ref name=Hartnett>Hartnett, John. ''Starlight, Time, and the New Physics''. Creation Book Publishers, 2007, pp. 34-36. ISBN 9780949906687.</ref>

Mercury has more or less no atmosphere, and many craters. <ref>John Gribbin, ''Companion to the Cosmos'' (Little, Brown & Company, 1996)</ref> It has no known moons.

Mercury has more or less no atmosphere, and many craters. <ref>John Gribbin, ''Companion to the Cosmos'' (Little, Brown & Company, 1996)</ref> It has no known moons.