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  2. Mesosphere - Wikipedia

    en.wikipedia.org/wiki/Mesosphere

    The exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually located at altitudes from 47 to 51 km (29 to 32 mi; 154,000 to 167,000 ft) above sea level, and the upper boundary (the mesopause) is usually from 85 ...

  3. List of nearest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_nearest_stars

    The closest encounter to the Sun so far predicted is the low-mass orange dwarf star Gliese 710 / HIP 89825 with roughly 60% the mass of the Sun. [4] It is currently predicted to pass 0.1696 ± 0.0065 ly (10 635 ± 500 au) from the Sun in 1.290 ± 0.04 million years from the present, close enough to significantly disturb the Solar System's Oort ...

  4. Poles of astronomical bodies - Wikipedia

    en.wikipedia.org/wiki/Poles_of_astronomical_bodies

    The location of the celestial poles of some selected Solar System objects is shown in the following table. [1] The coordinates are given relative to Earth's celestial equator and the vernal equinox as they existed at J2000 (2000 January 1 12:00:00 TT ) which is a plane fixed in inertial space now called the International Celestial Reference ...

  5. Outline of the Solar System - Wikipedia

    en.wikipedia.org/wiki/Outline_of_the_Solar_System

    The Sun, planets, moons and dwarf planets (true color, size to scale, distances not to scale) 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 ...

  6. Solar System - Wikipedia

    en.wikipedia.org/wiki/Solar_System

    The principal component of the Solar System is the Sun, a G-type main-sequence star that contains 99.86% of the system's known mass and dominates it gravitationally. [37] The Sun's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%.

  7. Solar coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Solar_coordinate_systems

    The Sun is a rotating sphere of plasma at the center of the Solar System. It lacks a solid or liquid surface, so the interface separating its interior and its exterior is usually defined as the boundary where plasma becomes opaque to visible light, the photosphere. Since plasma is gaseous in nature, this surface has no permanent demarcated ...

  8. Lower mantle - Wikipedia

    en.wikipedia.org/wiki/Lower_mantle

    The upper boundary is defined by the sharp increase in seismic wave velocities and density at a depth of 660 kilometers (410 mi). [8] At a depth of 660 km, ringwoodite (γ-(Mg,Fe) 2 SiO 4) decomposes into Mg-Si perovskite and magnesiowüstite. [8] This reaction marks the boundary between the upper mantle and lower mantle. This measurement is ...

  9. Star chart - Wikipedia

    en.wikipedia.org/wiki/Star_chart

    A star chart drawn 5000 years ago by the Indians in Kashmir, which also depict a supernova for the first time in human history. [7] The Nebra sky disk, a 30 cm wide bronze disk dated to 1600 BC, bears gold symbols generally interpreted as a sun or full moon, a lunar crescent, several stars including the Pleiades cluster and possibly the Milky Way.