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  2. Poles of astronomical bodies - Wikipedia

    en.wikipedia.org/wiki/Poles_of_astronomical_bodies

    In 2009 the responsible IAU Working Group decided to define the poles of dwarf planets, minor planets, their satellites, and comets according to the right-hand rule. [1] To avoid confusion with the "north" and "south" definitions relative to the invariable plane, the poles are called "positive" and "negative."

  3. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    The heliocentric ecliptic system describes the planets' orbital movement around the Sun, and centers on the barycenter of the Solar System (i.e. very close to the center of the Sun). The system is primarily used for computing the positions of planets and other Solar System bodies, as well as defining their orbital elements.

  4. Stability of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Stability_of_the_Solar_System

    The planets' orbits are chaotic over longer time scales, in such a way that the whole Solar System possesses a Lyapunov time in the range of 2~230 million years. [3] In all cases, this means that the positions of individual planets along their orbits ultimately become impossible to predict with any certainty.

  5. Universe - Wikipedia

    en.wikipedia.org/wiki/Universe

    The observable universe contains as many as an estimated 2 trillion galaxies [95] [96] [97] and, overall, as many as an estimated 10 24 stars [98] [99] – more stars (and earth-like planets) than all the grains of beach sand on planet Earth; [100] [101] [102] but less than the total number of atoms estimated in the universe as 10 82; [103] and ...

  6. Proper motion - Wikipedia

    en.wikipedia.org/wiki/Proper_motion

    In this diagram the radial velocity happens to be one of the Sun and object parting, so is positive. Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant ...

  7. Solar System - Wikipedia

    en.wikipedia.org/wiki/Solar_System

    [f] Six planets, seven dwarf planets, and other bodies have orbiting natural satellites, which are commonly called 'moons'. The Solar System is constantly flooded by the Sun's charged particles, the solar wind, forming the heliosphere. Around 75–90 astronomical units from the Sun, [g] the solar wind is halted, resulting in the heliopause.

  8. January's Rare Planet Parade Will Have These 3 Signs ... - AOL

    www.aol.com/januarys-rare-planet-parade-3...

    A rare six-planet parade is predicted to align in our night sky on Jan. 21 that will not only form a fascinating display from our view on Earth but will dazzle the cosmos in a way that affects ...

  9. 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 ...