Sedna is a large trans-Neptunian object, which as of 2012 was about three times as far from the Sun as Neptune. Sedna has the longest orbital period of any known large object in the Solar System, calculated at approximately 11,400 years. Its maximum speed is 4.64 km/s. Its orbit is extremely eccentric, with an aphelion (furthest distance from the Sun) estimated at 937 AU and a perihelion (closest distance from the Sun) at about 76 AU, the most distant perihelion ever observed for any Solar System object. (An "Astronomical Unit" (abbreviated as AU, is a unit of length equal to exactly 1 AU 149,597,870, 700 m or approximately the mean Earth-Sun distance.) The mass and radius of Sedna are not well known. Its orbit is shown in the figure below. Sedna aphelion perihelion Sun What is Va, the speed of Sedna at the aphelion? Va = km/s
