Comets are flying around the solar system. As they near the sun, they develop a tail as material is blown off by the solar wind. Most astronomers agree that comets cannot be more than 10,000 years old. They would have completely disappeared by now. Some scientists have recognized this as a serious problem for the theory that the earth is billions of years old, so they have proposed a new theory that new comets are constantly being introduced into the solar system to replace the old ones that burn out. They say they are coming from the "Oort Cloud.” No one has ever seen this Oort cloud, Oort never saw the Oort cloud! There is NO scientific evidence for its existence, but in their mind, this answers the serious problem the short lives of comets creates. There is a simpler answer, of course: the universe is NOT billions of years old!