Mercury crossed the sun on May 7, 2003 they called it a transit, a transit is like a solar eclipse, an eclipse is when the moon passes in front of the sun. Mercury has been known since the 3rd millennium B.C. Mariner 10 saw a shock wave called a Bow Shock in front of Mercury where the planet met the solar wind. Mariner 10 observed a small amount of helium, 1,000 km, maybe this is because by the solar wind and the breakdown of Mercury's crust. Mercury's gravity is 3.7 m/s ^ 2 (0.38 times Earth's). The reason that Mercury's doesn't have any moons is because Mercury's doesn't have that kind of gravity to hold them. The Sun is so massive and its powerful gravity would suck away Mercury's moons in a second, but big planets like Jupiter and Saturn have over (way over) 30 moons because they have such great gravity.

Mercury has almost no air. The diameter of Mercury is 3,025 miles, the weight is 330,200,000,000,000,000,000,000 kg, Mercury has 87,969 Earth days, one day on Mercury is 58,646 Earth days, the average distance from the sun to Mercury is 57 million km. Mercury is like a huge metal ball with a rocky crust, the core is made up of nickel and iron. Mariner 10 had three flybys near Mercury. This planet is located in our solar system. Mercury is about 4.5 billion years old.

Johann Hieronymus was the first to actually see Mercury and he drew drawings of it's features, but astronomer Eugenios Antoniadi drew the surface of Mercury in fantastic detail, his maps were used for 50 years. He used the strongest telescopes of his time and found out that the canals are actually optical illusions.

Mercury has so many things around it like planets Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The Sun takes up about  98% of the solar system, the planets take up about 2% of the space.

Mercury has been blown away by the Sun's solar winds, Mercury has so many craters people think that it looks like our moon, the reason that it has so many craters is because of asteroids hitting it. Mercury just had a transit on Wednesday, November 8, 2006!
 

Credits:

http://www.solarviews.com/eng/solarsys.htm

http://www.sciencemonster.com/planets_mercury.html

http://www.kidsastronomy.com/mercury.htm

http://www.windows.ucar.edu/tour/link=/mercury/statistics.html&edu=elem

http://amazing-space.stsci.edu/cgi-bin/search

hindows.ucar.edu/tour/link=/headline_universe/solar_system/stories_2003/images/mercury_transit_big_jpg_image.html&edu=elemttp://www.w

http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html

http://www.facts-about.org.uk/science-planet-mercury-planet-info.htm

http://www.windows.ucar.edu/tour/link=/mercury/Interior_Surface/Surface/mercury_s_image.html&edu=elem
 

http://www.solarviews.com/cap/sun/eclips91.htm

http://www.solarviews.com/cap/merc/antoniad.htm

http://www.windows.ucar.edu/tour/link=/mythology/images/head_hermes_jpg_image.html&edu=elem

http://www.windows.ucar.edu/tour/link=/missions/images/marin4_image.html&edu=elem

http://www1.jsc.nasa.gov/er/seh/mercury.html

Picture: http://www.windows.ucar.edu/tour/link=/headline_universe/solar_system/stories_2006/mercury_transit_nov_2006.html&edu=mid

1991 Solar Eclipse Picture - http://www.solarviews.com/cap/sun/eclips91.htm