2002 MS4

(307261) 2002 MS4 is a large classical Kuiper belt object and a possible dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. It was discovered in 2002 by Chad Trujillo and Michael Brown. 2002 MS4 has been observed 74 times, with precovery images back to 8 April 1954. As of 2019, 2002 MS4 is 46.5 AU from the Sun. It will reach perihelion, its closest point to the Sun, in 2122. At nearly 800 km in diameter, it is approximately tied (to within measurement uncertainties) as the largest unnamed object in the Solar System and is also tied as the largest known planetoid without a moon.