The long and short of it….. the orbital period of comets can range from long period comets like Comet McNaught, 92,700 years, to Comet Encke that zips around the Sun every 3.3 years.
Comet Hyakutake holds the record of having the longest tail, at a length of 560 million kilometres. This is almost double the size of the Great Comet of 1843 which previously held the record with a tail of 300 million kilometres. Mary Morton painted this comet (image above) as she saw it from Van Dieman's Land - now called Tasmania.
The Rosetta probe was intentionally crashed into Comet 67P/Churyumov-Gerasimenko in order to provide close-up photos on its final descent. The solar-powered spacecraft would not have enough energy to survive the trek back out into the solar system, where the comet is now heading.
Jupiter is a “cosmic vacuum cleaner.” Its gravitational influence causes comets and asteroids to collide with it. In 1994 Comet Shoemaker-Levy crashed into the planet. Without Jupiter, the probability of impacts with the inner planets would be much greater.
A comet’s tail always points away from the Sun.