Although its perihelion is extremely close to the mean distance of Ceres and Pallas , a collision between Hygiea and its bigger companions is impossible because at that distance they are always on opposite sides of the ecliptic . Although its perihelion is extremely close to the mean distance of Ceres and Pallas , a collision between Hygiea and its larger companions is impossible because at that distance they are always on opposite sides of the ecliptic .