Five-planet Nice model distant massive ninth planet is responsible for the alignment of the perihelia of several trans-Neptunian objects with semi-major axes greater than 250 AU. Although the mechanism for the ejection of the fifth giant planet in the five-planet Nice model is reminiscent of the origin of Planet Nine, with a gravitational instability including an encounter with Jupiter, it is unlikely to be the same planet. The estimated timing of the capture of Planet Nine onto its distant orbit, three to ten million years after the formation of the Solar System, when the Sun was still in its birth cluster, is inconsistent
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