After nearly a full orbit of observation, "ice giant" Uranus began to show irregularities that puzzled and even alarmed astronomers. English and French mathematicians soon engaged in a spirited contest to determine the cause, simultaneously proposing that a planet beyond was perturbing the motion of Uranus. Finally in 1846, the new planet was observed and later named in honor of the Roman god Neptune, or Greek god Poseidon, ruler of the ocean.