Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Dioretsa is a centaur discovered in 1999 notable for its unusual orbit, which is highly eccentric and retrograde. Its name is the word 'asteroid' spelled backwards to reflect this fact. It is one of twenty or so known minor planets in the Solar System that have a retrograde orbit see the List of notable asteroids. Dioretsa's orbit is otherwise similar to a comet's; it has a perihelion of 2.4 AU and an aphelion of 45.3 AU. This has led to speculation that Dioretsa was originally an object from the Oort cloud.