Discovery and exploration of the Solar System Discovery and exploration of the Solar System Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets including Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust. For many thousands of years, astronomers maintained a geocentric world view and did not recognize the existence of a Solar System. Most believed Earth was stationary at the center of the Universe and categorically different from the divine or ethereal objects
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