You have a better chance of being in a plane crash than being in the 1 in 5,000 and greater chance of being killed in an impact. Although these facts are true, there is a chance, a slight, very slight one at that, that one could hit at any time. Moreover, there are more people working in a single McDonald's restaurant than there are people searching for asteroids. We have to make a better effort for our future's sake. Comets move faster than asteroids and like Hale-Bopp and Hyakutake, were clocked at over 100,000 mph.
Different comets move at different speeds.
They can move as slow as 50,000 mph. Comets travel in more eccentric orbits, like ovals with their tails of ionized gas and dust trailing them. That is pointing away from the sun. This is because of the solar wind. These tails only appear when they get near the sun, when the heat melts the surface.