Triton, the biggest of Neptune's 13 moons, orbits in the opposite direction of the planet's rotation, the only large moon in our solar system to do so. It was discovered #OTD in 1846 by British astronomer William Lassell. . . . . . . . . . #triton #planet #space #discover #neptune #cosmos #NASA #solarsystem #universe #discovery #today #science #todayinscience #history #sciencehistory #astronomy #nightsky #star #tbt