Asteroid
The dwarf planet Ceres is by far the largest asteroid, with a diameter of . The next largest are 4 Vesta and 2 Pallas, both with diameters of just over . Vesta is the only main-belt asteroid that can, on occasion, be visible to the naked eye. On some rare occasions, a near-Earth asteroid may briefly become visible without technical aid; see 99942 Apophis.
2018 CY2
is an Apollo asteroid. Apollo's cross the orbit of Earth and are the largest group of near-Earth objects with nearly 10 thousand known members. It orbits the Sun at a distance of 0.92–1.34 AU once every 14 months (438 days; semi-major axis of 1.13 AU). Its orbit has an eccentricity of 0.18 and an inclination of 27° with respect to the ecliptic. It is, however, not a Mars-crossing asteroid, as its aphelion of 1.34 AU is less than the orbit of the Red Planet at 1.666 AU. The body's observation arc begins its first observation at Mount Lemmon in February 2018.