Fifth planet (hypothetical) orbit as defined by the Titius–Bode law. Between 1845 and 1851, eleven additional asteroids were discovered and Jupiter had become the twentieth planet. At this point, astronomers began to classify asteroids as minor planets. Following the reclassification of the asteroids in their own group, Jupiter became the fifth planet once again. With the redefinition of the term "planet" in 2006, Ceres is now considered a dwarf planet. The disruption theory suggests that a planet which was positioned between Mars and Jupiter was destroyed, resulting in the asteroid belt between these planets. Scientists in the 20th century dubbed this hypothetical planet
Fifth Planet (novel) expedition includes the first woman in space. This fictional milestone was eclipsed by reality soon after publication, when Valentina Tereshkova became the first woman in space on Vostok 6 in June 1963. Fifth Planet (novel) Fifth Planet is a science fiction novel written by astrophysicist Sir Fred Hoyle and his son Geoffrey Hoyle. Another star is due to pass close to the sun, close enough for conventional spacecraft to reach it. The first planets observed are four gas giants, but then an inner 'Fifth Planet' is found. Signs of chlorophyll are detected, suggesting that it supports life. Rival Soviet and