 Comets come at us from all directions. And we have seen that they have two kinds of orbits, long and short. Long period comets can take thousands of years and have unpredictable orbits. Here are a few of them. Sighting Spring visited us in 2013 and 2014 and came very close to Mars. Those orbiters, at the time, detected hundreds of kilograms per hour of the comet's dust. Sighting Spring won't be back for millions of years. Hellbop was one of the brightest comets in decades. It was visible to the naked eye for 18 months. That was twice as long as the previous record held by the Great Comet of 1811. Hellbop is expected to be back in the year 4385. Lovejoy 2014 approached Earth to within half the distance from the Sun. It had traveled inbound for 11,000 years and it won't return for almost 20,000 more years. Short period comets, also known as periodic comets, take as few as three and as long as 200 years. They are also much more predictable. 67P has an orbital period of just under six and a half years. At the end of this segment we'll be covering the Rosetta mission that landed a probe on this comet in 2014. Anki orbits the Sun in just 3.3 years. It is thought to be the originator of several meteor showers here on Earth. And we have already discussed Halley's Comet. My grandchildren will see it in 2061. The fact that there are two kinds of orbits, long and short, led to the idea that comets originate from two different places. With the short period comets coming from the Kuiper Belt and the longer period comets coming from a proposed area called the Oort Cloud.