History of Mercury/Planet

	Revision 16 . . December 13, 2001 11:12 am by Wayne Hardman [added a bit about why it was thought mercury was tidally locked]
	Revision 15 . . (edit) December 11, 2001 5:46 am by Bryan Derksen [bypassing Venus link page]
	Revision 14 . . (edit) November 30, 2001 11:22 am by Bryan Derksen
	Revision 13 . . (edit) November 21, 2001 7:28 am by (logged).128.188.xxx
	Revision 12 . . November 20, 2001 2:38 pm by Eob
	Revision 11 . . November 20, 2001 9:05 am by Eob [Surface Area]
	Revision 10 . . (edit) November 5, 2001 9:12 am by Bryan Derksen [updated solar system navbar link to mars]

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Mercury is one of the least-studied of the solar system's planets. It was visited by only one spacecraft, [Mariner 10]?, which flew past it on three occasions in 1974 and 1975. Only 45% of the planet's surface was mapped, and it is located too near the sun for existing telescopes to conduct further mapping from Earth. Until radar observations in 1965 proved otherwise it was thought that Mercury was [tidally locked]? with the Sun, rotating once for each orbit and keeping the same face directed towards the sun at all times. Instead, Mercury is in a 3:2 resonance, rotating three times for every two revolutions around the sun.

Mercury is one of the least-studied of the solar system's planets. It was visited by only one spacecraft, [Mariner 10]?, which flew past it on three occasions in 1974 and 1975. Only 45% of the planet's surface was mapped, and it is located too near the sun for existing telescopes to conduct further mapping from Earth. Until radar observations in 1965 proved otherwise it was thought that Mercury was [tidally locked]? with the Sun, rotating once for each orbit and keeping the same face directed towards the sun at all times. Instead, Mercury is in a 3:2 resonance, rotating three times for every two revolutions around the sun. The original reason astronomers thought it was tidally locked was because whenever Mercury was best placed for observation, it was always at the same point in it's 3:2 resonance, so showing the same face, which would be also the case if it was totally locked.