2005 HC4 is the asteroid with the second-smallest perihelion and the asteroid with the smallest known perihelion of any known object orbiting the Sun from 2005 to 2024 (except sungrazing comets). Its extreme orbital eccentricity brings it to within 0.071 AU of the Sun (23% of Mercury's perihelion) and takes it as far as 3.562 AU from the Sun (well beyond the orbit of Mars). Since then, another asteroid, , has been found to have a closer perihelion, at about 0.070 AU. Due to its very small perihelion and comparably large aphelion, achieves the fastest speed of any known asteroid bound to the Solar System with a velocity of 157 km/s (565,000 km/h; 351,000 mi/h) at perihelionAs calculated with the vis-viva-equation : where:
v is the relative speed of the two bodies r is the distance between the two bodies a is the semi-major axis (a > 0 for ellipses, a = ∞ or 1/a = 0 for parabolas, and a < 0 for hyperbolas) G is the gravitational constant M is the mass of the central body (there are comets, however, which obtain much higher speeds).
See also List of Mercury-crossing minor planets List of Venus-crossing minor planets Apollo asteroids List of Mars-crossing minor planets
References (K05H04C)
External links