Neptune Day - 9/23

Neptune Day (On this day in 1846, Johann Galle at the Berlin Observatory, using calculations by French mathematician Urbain Le Verrier, discovered Neptune at the predicted location. British mathematician John Couch Adams had also independently calculated the location, and now all three are credited as discoverers. It cannot be observed with the naked eye and is the only planet in our solar system discovered through mathematical prediction, based on irregularities in Uranus's orbit. It orbits the outermost region of the solar system over approximately 165 years, and its name comes from the Roman god of the sea, 'Neptunus'.)