Mercury

2011-05-02T04:55:56Z

Shubhanshu:

{{Planet
|image=Murcurt.jpg
|caption=Reprocessed Mariner 10 data was used to produce this image of Mercury. The smooth band is an area of which no images were taken.
|discname=Known to ancients
|origname=Roman messenger god and prince of thieves
|primary=Sun
|order=1
|periapsis=46,000,000 km (0.307 AU)
|apoapsis=70,000,000 km (0.468 AU)jljkljkl,hklh
|semimajor=57,909,175 km (0.387 AU)
|bode=0.4 AU
|eccentricity=0.20563069
|sidereal=87.96934 da (0.241 a)
|synodic=115.8776 da (0.317 a)
|orbitspeed=47.36 km/s
|inclination=7.00487°
|reference=the ecliptic
|siderealday=58.6462 da
|solarday=175.93868 da
|axialtilt=0°
|mass=3.30 * 1023 kg (5.522% earth)
|density=5427 kg/m³
|meanradius=2439.7 km
|surfacegrav=2.78 m/s² (0.283 ''g'')
|escapespeed=4.25 km/s
|surfacearea=75,000,000 km² (14.704% earth)
|mintemp=90 K
|meantemp=452 K
|maxtemp=700 K
|moons=None known
|composition=Iron, Silicate
|color=Reddish
|mfd=0.033 G (3.3 * 10-6 T)<ref name=mercuryfact>Williams, David R. "[http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html Mercury Fact Sheet]." National Space Science Data Center, [[National Aeronautics and Space Administration|NASA]], November 30, 2007. Accessed May 29, 2008.</ref>
|pmdm=3.8 * 1019 N-m/T<ref name=Humphreys2>Humphreys, D. R. "[http://creationontheweb.com/content/view/5976/ Mercury's Magnetic Field is Young]!" [[Creation Ministries International]], August 26, 2008. Accessed October 2, 2008.</ref>
|cmdm=7.5 * 1022 N-m/T<ref name=Humphreys>Humphreys, D. R. "[http://www.creationresearch.org/crsq/articles/21/21_3/21_3.html The Creation of Planetary Magnetic Fields]." ''[[Creation Research Society Quarterly]]'' 21(3), December 1984. Accessed April 29, 2008.</ref>
|mdt=812.6 a<ref name=calc>Calculated from observed present magnetic dipole moment and expected magnetic dipole moment at creation.</ref>
|mhl=563.3 a<ref name=calc/>
}}
:''This article is about the planet Mercury. For information about the chemical element see [[Mercury (element)]].''
:''For information about the NASA project, see [[Project Mercury]].''

[[Mercury]] is the smallest planet in the [[Solar System]], and it is the closest to the [[Sun]]. It orbits the [[Sun]] in 88 (Earth) days. It rotates on its axis every 58.6 days,<ref>"The theory that Mercury is in [[synchronous rotation]] with its orbital motion was shattered in 1965. Astronomers Gordon Pettengill and Rolf Dyce used a radio telescope to make radar observations of Mercury’s spin rate. They found that Mercury’s rotation period is only 58.6 Earth days, not the 88 days accepted for nearly a century." [http://btc.montana.edu/messenger/elusive_planet/modern_times.htm]</ref> which is 3 rotations for every two orbits (called "3:2 resonance"). It can be seen from [[Earth]] only at sunrise and sunset.<ref name="spacemag">[http://www.space.com/spacewatch/mercury_view_030404.html Seeing Mercury at sunset], April 2003</ref>

Mercury is one of the five brightest planets.

== Ancient History ==
As with the other planets of the solar system, it was named after after Roman mythology, in this case the messenger god Mercury who is known as [[Hermes]] in Greek.

In the pre-Christian era, the Greeks actually gave the planet two different names, as it was believed to be two different objects. The ancients did not realize that it could alternately appear on one side of the Sun and then the other. Mercury was called Hermes when in the evening sky, but was known as Apollo when it appeared in the morning. It is said that [[Pythagoras]], about the fifth century B.C., pointed out that they were one and the same.<ref name="spacemag"/>

== Composition ==
Mercury's core is made of molten metal, much like the Earth's. The molten [[Iron]] core generates the planet's magnetic field.

== Orbital oddities ==
Mercury has a very elliptical orbit. At its farthest distance from the Sun, it is nearly 50% farther than at its nearest distance to the Sun. <ref>http://astroprofspage.com/archives/139</ref>

The [[precession]] of Mercury's eccentric orbit was detectable to 19th century astronomers.<ref name=Wudka>Wudka, Jose. "[http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node98.html Precession of the perihelion of Mercury]." September 24, 1998. Accessed April 17, 2008.</ref><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.

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=Hartnett>Hartnett, John. ''Starlight, Time, and the New Physics''. Creation Book Publishers, 2007, pp. 34-36. ISBN 9780949906687.</ref><ref name=Wudka/><ref name=Britannica/> 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.

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.

==Magnetic Field==
A curiosity of the planet is its magnetic field, which is about 1% that of Earth's. Scientists were perplexed to discover its existence, speculating that planet's outer core consisted of liquid iron. However, because it is relatively small and hot, such an outer core would long ago have expired. That Mercury is so intensely cratered would also suggest that Mercury should long ago have given up its magnetic field because of its extreme apparent age.

Thus, according to current scientific understandings, the existence of Mercury's magnetic field presents a serious theoretical problem for [[uniformitarian]] models of the creation of the Solar System.<ref name=Psarris>Psarris, Spike, ''Our Solar System: Evidence for Design'', Seattle Creation Conference, 2006.</ref><ref>Franco, Lucia M. "[http://astro.uchicago.edu/home/web/lucia/a100/lectures/mercury.html Lecture 10.1: Mercury]." ''Astronomy 100 at Indiana University Northwest'', [[Indiana University]], 1996. Accessed April 17, 2008.</ref> The problem of Mercury's magnetic field is more acute when one considers that Mars, which is slightly larger than Mercury and spins much faster, has a much weaker magnetic field.

[[Creationist]] [[Russell Humphreys]] has an alternative theory: that planetary magnetic fields do not form by dynamo action, and Mercury's relatively wide and conductive core has preserved its magnetic field. The cores of Mars and Venus are smaller, and thus the magnetic fields have decayed more rapidly.<ref name=Humphreys/> Nevertheless, the decay of Mercury's magnetic field, according to Humphreys, is quite rapid.

Accordingly, in 1984 Humphreys boldly declared:{{cquote|Mercury's decay rate is so rapid that some future probe could detect it fairly soon. In 1990 the planet's magnetic moment should be 1.8 percent smaller than its 1975 value.<ref name=Humphreys/>}}

In fact, according to Humphreys' extrapolations of the decay time and half-life of the magnetic field of Mercury, the [[magnetic dipole moment]] in 2008 should be ''four'' percent smaller than that measured in 1975 by Mariner 10. Specifically, this should be (4.5 +/- 0.25) * 1019 N-m/T.

On January 14, 2008, [[MESSENGER]] made rendezvous with Mercury and measured its magnetic field. This rocket probe's measurements are consistent with a magnetic dipole moment of (3.8 +/- 0.7) * 1019 N-m/T. This represents a significant decline from the Mariner 10 measurement, because the two measurements differ by more than the sum of their respective tolerances. More to the point, the higher tolerance range of the current measurement lies well within the predicted magnetic dipole moment that Mercury should have at present. If, on the other hand, the trkklkljkljkl

== External links ==

*[http://www.solarviews.com/eng/terms.htm Glossary]
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==Notes==
{{reflist|2}}

* [http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mercury&Display=Overview NASA "Mercury"]
* [http://www.answersingenesis.org/creation/v26/i4/mercury.asp Mercury — the tiny planet that causes big problems for evolution]

{{Solarsystem}}
[[Category:Astronomy]]
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