The beautiful and blue planet Neptune has completed 1 full orbit around the Sun since its' discovery on Spetember 23-24, 1846. Neptune was discovered as a result of the gravitational influences its had on the planet Uranus. Astronomers were able to calculate the predicted position of the unknown planet and started searching. Neptune was found within 1 degree of the predicted positon.
Pretty amazing to consider all of this calculation was done by paper and pen - no calculators, no computers, no digital cameras, no computer controlled telescopes. Amazing and a tribute to the state of science at the time.
Read More About It: http://www.skyandtelescope.com/community/skyblog/observingblog/125207704.html
UPDATE: Hubble Space Telescope has taken "Birthday" images of Neptune: http://hubblesite.org/newscenter/archive/releases/2011/19
Sky Guy in VA