请用英语介绍下水星。

Deviated from the orbit of Mercury Zhengyuan great extent, the sun only recently Pitch 46001000 meters, far points on 7 10001000 meters have, in recent days at the track it in a very slow speed by running forward precession around the sun (precession: Axis from moving into the spring equinox, the slow westward run, the annual rate of 0.2 ", about 25,800 years running a week to return to the star than the short phenomenon. Precession, and the two planets precession, which is determined by planetary gravity of the ecliptic Arising from the changes.) In the 19th century, astronomers radius of the orbit of Mercury had a very careful observation, but were unable to use Newton's mechanics to make the appropriate explanation. Exists in the actual observation to notice the value and values between the Is a subtle difference in the secondary (per one-seventh of the Millennium difference) but plagued by astronomers for decades the issue. Some people think that in and around the orbit