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The outer planets' orbits are chaotic over longer timescales, with a Lyapunov time in the range of 2–230 million years. [105] In all cases, this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer becomes uncertain).
French philosopher and mathematician René Descartes was the first to propose a model for the origin of the Solar System in his book The World, written from 1629 to 1633.. In his view, the universe was filled with vortices of swirling particles, and both the Sun and planets had condensed from a large vortex that had contracted, which he thought could explain the circular motion of the plane
The outer planets Jupiter, Saturn, Uranus and Neptune, compared to the inner planets Earth, Venus, Mars, and Mercury at the bottom right The four outer planets, called giant planets or Jovian planets, collectively make up 99% of the mass orbiting the Sun. [ h ] All four giant planets have multiple moons and a ring system, although only Saturn's ...
The age of Earth is estimated to be 4.54 ± 0.05 billion years (4.54 × 10 9 years ± 1%). [1] [2] ... soon after the solar disk and the planets formed.
According to evidence from radiometric dating and other sources, Earth formed about 4.54 billion years ago. [7] [8] [9] The current dominant theory of planet formation suggests that planets such as Earth form in about 50 to 100 million years but more recently proposed alternative processes and timescales have stimulated ongoing debate in the planetary science community. [10]
Counting them among the planets became increasingly cumbersome. Eventually, they were dropped from the planet list (as first suggested by Alexander von Humboldt in the early 1850s) and Herschel's coinage, "asteroids", gradually came into common use. [139] Since then, the region they occupy between Mars and Jupiter is known as the asteroid belt.
The earliest scientist to study and produce a paper using crater counting as an age indicator was Ernst Öpik, an Estonian astronomer and astrophysicist. [6] Ernst Öpik utilized the crater counting method to date the Moon's Mare Imbrium to be approximately 4.5 billion years of age, estimating the maria to be about 1000 years younger than the contintentes. [6]
Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution