Neptune at magnitude 7.8 requires binoculars or a telescope and appears as a tiny blue dot of 2.3 arcsec — distinguishable from stars by its steady, non-twinkling light and subtle disk at high magnification. Its deep blue color, richer than Uranus, comes from methane and an unknown chromophore. Neptune was the first planet found by mathematical prediction: John Couch Adams and Urbain Le Verrier independently calculated its position from perturbations in Uranus's orbit. Johann Galle found it at the Berlin Observatory on September 23, 1846, within one degree of Le Verrier's prediction. Named for the Roman god of the sea. Voyager 2 made the only flyby in August 1989, discovering six new moons, a faint ring system, and the Great Dark Spot — a storm system the size of Earth with the fastest winds ever measured in the solar system (2,100 km/h). That storm has since vanished, replaced by others observed by HST. Triton, Neptune's largest moon, has retrograde orbit (likely a captured Kuiper Belt object) and active nitrogen geysers photographed by Voyager. Triton is visible in 200mm telescopes as a faint point near the planet. Neptune takes 165 years to orbit the Sun; it completed its first full orbit since discovery in 2011.