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  2. Planetary system - Wikipedia

    en.wikipedia.org/wiki/Planetary_system

    An artist's concept of a planetary system. A planetary system is a set of gravitationally bound non-stellar bodies in or out of orbit around a star or star system.Generally speaking, systems with one or more planets constitute a planetary system, although such systems may also consist of bodies such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals [1] [2] and ...

  3. Nebular hypothesis - Wikipedia

    en.wikipedia.org/wiki/Nebular_hypothesis

    The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems). It suggests the Solar System is formed from gas and dust orbiting the Sun which clumped up together to form the planets.

  4. Geology of solar terrestrial planets - Wikipedia

    en.wikipedia.org/wiki/Geology_of_solar...

    The Solar System is believed to have formed according to the nebular hypothesis, first proposed in 1755 by Immanuel Kant and independently formulated by Pierre-Simon Laplace. [2] This theory holds that 4.6 billion years ago the Solar System formed from the gravitational collapse of a giant molecular cloud. This initial cloud was likely several ...

  5. Formation and evolution of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Formation_and_evolution_of...

    The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud, [9] most likely at the edge of a Wolf-Rayet bubble. [10] The cloud was about 20 parsecs (65 light years) across, [9] while the fragments were roughly 1 parsec (three and a quarter light-years) across. [11]

  6. Solar System - Wikipedia

    en.wikipedia.org/wiki/Solar_System

    Diagram of the early Solar System's protoplanetary disk, out of which Earth and other Solar System bodies formed. The Solar System formed at least 4.568 billion years ago from the gravitational collapse of a region within a large molecular cloud. [b] This initial cloud was likely several light-years across and probably birthed several stars. [14]

  7. Protoplanetary disk - Wikipedia

    en.wikipedia.org/wiki/Protoplanetary_disk

    [18] [19] The formation of planets and moons in geometrically thin, gas- and dust-rich disks is the reason why the planets are arranged in an ecliptic plane. Tens of millions of years after the formation of the Solar System, the inner few AU of the Solar System likely contained dozens of moon- to Mars-sized bodies that were accreting and ...

  8. Secondary atmosphere - Wikipedia

    en.wikipedia.org/wiki/Secondary_atmosphere

    If the planet is too small, then its gravity isn't strong enough to hold onto all of the gas it gained during formation. This causes the primary atmosphere, which is mostly made of hydrogen (H 2) from the nebula the solar system formed in, [2] to run away and leave the planet entirely. Hydrogen, being the lightest element, will naturally escape ...

  9. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.