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This is the boundary of the Solar System to interstellar space. The outermost region of the Solar System is the theorized Oort cloud, the source for long-period comets, extending to a radius of 2,000–200,000 AU. The closest star to the Solar System, Proxima Centauri, is 4.25 light-years (269,000 AU) away.
The inner Solar System's period of giant impacts probably played a role in Earth acquiring its current water content (~6 × 10 21 kg) from the early asteroid belt. Water is too volatile to have been present at Earth's formation and must have been subsequently delivered from outer, colder parts of the Solar System. [63]
The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. [1] It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation.
Fundamental to modern cosmology is the well-accepted theory of the Big Bang, wherein our Universe began at a single point in time, and thereafter expanded over the course of 13.8 billion years [85] to its present condition. [86] The concept of the Big Bang can be traced back to the discovery of the microwave background radiation in 1965. [86]
The universe consists of a plasma of nuclei, electrons, and photons; temperature is too low to create electron-positron pairs (or any other pairs of massive particles), but too high for the binding of electrons to nuclei. Recombination: 18 ka ~ 370 ka 6000 ~ 1100 4000 K (0.4 eV) Electrons and atomic nuclei first become bound to form neutral ...
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 following outline is provided as an overview of and topical guide to the Solar System: Solar System – gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets (including Earth), with the remainder being ...
The Big Bang theory, which explains the Evolution of the Universe from a hot and dense state, is widely accepted by physicists.. In astronomy, cosmogony is the study of the origin of particular astrophysical objects or systems, and is most commonly used in reference to the origin of the universe, the Solar System, or the Earth–Moon system.