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
Akaa Solar System Scale Model Akaa Solar System Scale Model Akaa Solar System Scale Model is located at the center of the city of Akaa, Finland. The sun is located at the school campus of Toijalan Yhteiskoulu –school in Toijala district. The scale of the model is 1 : 3 000 000 000, meaning that each centimetre in the scale model represents 30 000 km in real life. The Sun is 464 mm in diameter and the Earth is 4 mm in diameter and located 49.86 meters away from the sun. Neptune is 1500 meters away from the Sun, for example. Akaa Solar System Scale