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Discovery of the anomolous perihelion shift of Mercury
Urbain Le Verrier discovers the anomolous perihelion shift of Mercury. -
The first sighting of Vulcan
The first sighting of Vulcan, a planet thought to orbit inside Mercury. -
16 degrees apart
The Sun, the Moon, Mercury, Venus, Mars, Jupiter & Saturn are aligned within 16 degrees of each other. -
The first radar measurment of relativistic time delays to Mercury
Irwin Shapiro makes the first radar measurment of relativistic time delays to Mercury -
Mariner 10
Boeing receives contract for Mariner 10, Mercury exploration -
Mariner 10 passes
Mariner 10 passes by and photographs Mercury. -
The Planet Definition"
The "Planet Definition" Resolution was put to the 2006 General Assembly of the International Astronomical Union. The outcome decided the defintiion of what objects in the Solar System should be classified as "Planets". Pluto looses its status as a Planet retuning the total number of "Planets" in our solar system to eight.