Halley’s comet, which passes around the Sun every 76 years, has an elliptical orbit. When closest to the Sun (perihelion) it is at a distance of 8.823 times 10^{10}; {rm{m}} and moves with a speed of 54.6 {rm km}/{rm s}. The greatest distance between Halley’s comet and the Sun (aphelion) is 6.152 times 10^{12}; {rm{m}}.