Fifth planet (hypothetical) Fifth planet (hypothetical) In the history of astronomy, a handful of Solar System bodies have been counted as the fifth planet from the Sun. Under the present definition of a planet, Jupiter is counted as the fifth. There are three main ideas regarding hypothetical planets between Mars and Jupiter. During the early 19th century, as asteroids were discovered, they were considered planets. Jupiter became the sixth planet with the discovery of Ceres in 1801. Soon, three more asteroids, Pallas (1802), Juno (1804), and Vesta (1807) were discovered. They were counted as separate planets, despite the fact that they shared an
The Magic School Bus Lost in the Solar System The Magic School Bus Lost in the Solar System The Magic School Bus Lost in the Solar System is the fourth book in Joanna Cole and Bruce Degen's "The Magic School Bus" series. The book depicts arguably the most well-known adventure of the series and introduces the character of Janet. Ms. Frizzle's class is learning about the solar system and Arnold's unpleasant cousin Janet, who constantly raves about herself, has joined them. The Friz decides to take the kids on a field trip to the planetarium, but, once they get there, they find the planetarium is closed. However, on the