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The Milky Way [c] is the galaxy that ... stars decreases with distance from the center of the Milky Way. ... the night sky of a hypothetical planet within the Milky ...
List of nearest galaxies. This is a list of known galaxies within 3.8 megaparsecs (12.4 million light-years) of the Solar System, in ascending order of heliocentric distance, or the distance to the Sun. This encompasses about 50 major Local Group galaxies, and some that are members of neighboring galaxy groups, the M81 Group and the Centaurus A ...
The Sun is part of one of the Milky Way's outer spiral arms, known as the Orion–Cygnus Arm or Local Spur. [271] [272] It is a member of the thin disk population of stars orbiting close to the galactic plane. [273] Its speed around the center of the Milky Way is about 220 km/s, so that it completes one revolution every 240 million years. [270]
A 2013 study by Ravi Kumar Kopparapu put η e, the fraction of stars with planets in the HZ, at 0.48, [4] meaning that there may be roughly 95–180 billion habitable planets in the Milky Way. [120] However, this is merely a statistical prediction; only a small fraction of these possible planets have yet been discovered. [121]
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 Solar System Portal. The Sun and planets of the Solar System (distances not to scale) The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
It had been determined that the stars were much farther away than the planets. Saturn: Planet of the Solar System 1619 − 1781 10 AU From Kepler's Third Law, it was finally determined that Saturn is indeed the outermost of the classical planets, and its distance derived. It had only previously been conjectured to be the outermost, due to it ...
The Oort cloud (/ ɔːrt, ʊərt /), [1] sometimes called the Öpik–Oort cloud, [2] is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). [3][note 1][4] The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor ...