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  2. Neptune - Wikipedia

    en.wikipedia.org/wiki/Neptune

    Neptune's internal structure resembles that of Uranus. Its atmosphere forms about 5 to 10% of its mass and extends perhaps 10 to 20% of the way towards the core. Pressure in the atmosphere reaches about 10 GPa, or about 10 5 atmospheres. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere. [30]

  3. Apparent retrograde motion - Wikipedia

    en.wikipedia.org/wiki/Apparent_retrograde_motion

    Apparent retrograde motion is the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the ...

  4. Discovery of Neptune - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_Neptune

    John Herschel almost discovered Neptune the same way his father, William Herschel, had discovered Uranus in 1781: by chance observation. In an 1846 letter to Wilhelm Struve, John Herschel states that he observed Neptune during a sweep of the sky on July 14, 1830. Although his telescope was powerful enough to resolve Neptune into a small blue ...

  5. 5 planets are about to be retrograde at the same time. What ...

    www.aol.com/news/5-planets-retrograde-same-time...

    The summer of 2024 will be a wild ride, astrologically speaking — and for more reasons than just the rare super blue moon that rose in August.. A total of five planets are going retrograde ...

  6. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Animation showing the difference between a sidereal day and a solar day. Sidereal time ("sidereal" pronounced / saɪˈdɪəriəl, sə -/ sy-DEER-ee-əl, sə-) is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky.

  7. Pluto - Wikipedia

    en.wikipedia.org/wiki/Pluto

    Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most- massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is less massive than Eris.

  8. Rotation period (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Rotation_period_(astronomy)

    In astronomy, the rotation period or spin period[1] of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the sidereal rotation period (or sidereal day), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars (inertial space).

  9. Triton (moon) - Wikipedia

    en.wikipedia.org/wiki/Triton_(moon)

    Triton dominates the Neptunian moon system, with over 99.5% of its total mass. This imbalance may reflect the elimination of many of Neptune's original satellites following Triton's capture. [4][5] Triton (lower left) compared to the Moon (upper left) and Earth (right), to scale. Triton is the seventh-largest moon and sixteenth-largest object ...