Changes

The [[precession]] of Mercury's eccentric orbit was detectable to 19th century astronomers.<ref name=Britannica>"[http://www.britannica.com/eb/article-241978/Mercury Mercury: Mercury in tests of relativity]."  In "Mercury," ''Encyclopædia Britannica'', 2008. Encyclopædia Britannica Online. 17 April 2008</ref>

The [[precession]] of Mercury's eccentric orbit was detectable to 19th century astronomers.<ref name=Britannica>"[http://www.britannica.com/eb/article-241978/Mercury Mercury: Mercury in tests of relativity]."  In "Mercury," ''Encyclopædia Britannica'', 2008. Encyclopædia Britannica Online. 17 April 2008</ref>

It was the study of this planet's orbit that [[Albert Einstein]] claimed 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 5599.7 arc-seconds per century, whereas [[Sir Isaac Newton|Newtonian]] physics alone would predict 5558.8 (comprised of the gravitational pull of the other planets on top of [[axial precession]]). This gives a discrepancy of -40.9 between theoretical models and real observations.

It was the study of this planet's orbit that [[Albert Einstein]] claimed 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 574.10±0.65 arc-seconds per century relative to the inertial celestial reference frame. However [[Sir Isaac Newton|Newtonian]] physics alone would predict 531.63±0.69 arc-seconds (comprised of the gravitational pull of the other planets on top of [[axial precession]]). This gives a discrepancy of 42.47 arc-seconds between Newtonian models and observations.

Astronomers of the period hypothesized 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 supposedly accounts for 43 arc-seconds of precession and obviated the need to look for any unseen asteroids or innermost planet.<ref name=Britannica/><ref name=Hartnett>Hartnett, John. ''Starlight, Time, and the New Physics''. Creation Book Publishers, 2007, pp. 34-36. ISBN 9780949906687.</ref> However, the theoretical error in the relativity calculation (stated to be around 0.04<ref name="">Iorio, L., ''On the possibility of measuring the solar oblateness and some relativistic effects from planetary ranging'', 2004</ref>) is much less than the discrepancy which results (2.1 arc-seconds). So, while scientists tell us that the theory of relativity solved the problem perfectly, elementary analysis of the figures indicates that it only luckily landed in the ballpark, and is still out by around 50 times the supposed tolerance in the calculations.

Astronomers of the period hypothesized 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 supposedly accounts for 43 arc-seconds of precession and obviated the need to look for any unseen asteroids or innermost planet.<ref>https://www.math.washington.edu/~morrow/papers/Genrel.pdf

, Accessed 13/12/16</ref><ref name=Britannica/><ref name=Hartnett>Hartnett, John. ''Starlight, Time, and the New Physics''. Creation Book Publishers, 2007, pp. 34-36. ISBN 9780949906687.</ref> The theoretical error in the relativity calculation is stated to be around 0.04 arc-seconds<ref name="">Iorio, L., ''On the possibility of measuring the solar oblateness and some relativistic effects from planetary ranging'', 2004</ref>). propagating the error on measurements (e.g. the positions and speeds of planets have some uncertainty in them so the Newtonian prediction has some error in it) through produces a theoretical value of 574±0.69 arc-seconds. This is within the supposed tolerance of the observations.

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.