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
Solar cycle 24 to trigger a radio blackout. Larger than the planet Jupiter, the AR 12192 sunspot was visible during a partial solar eclipse seen in North America. The sun emitted a mid-level solar flare, an M7.9-class, peaking at 4:16 a.m. EDT on June 25, 2015. In early November 2015, solar flares disrupted the air traffic control system in central and southern Sweden, causing heavy delays for passengers. A sunspot group originally attributed to the new solar cycle 25 is observed. The sunspot numbers continue to decline. During 2016, there were 26 days with no sunspots (preliminary numbers). As of 31 March, preliminary