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  2. Neptune - Wikipedia

    en.wikipedia.org/wiki/Neptune

    Neptune is the eighth and farthest known planet from the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to its fellow ice giant Uranus, Neptune is slightly more massive, but denser and smaller.

  3. Rotation period (astronomy) - Wikipedia

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

    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 ...

  4. Poles of astronomical bodies - Wikipedia

    en.wikipedia.org/wiki/Poles_of_astronomical_bodies

    Venus rotates clockwise, and Uranus has been knocked on its side and rotates almost perpendicular to the rest of the Solar System. The ecliptic remains within 3° of the invariable plane over five million years, [ 2 ] but is now inclined about 23.44° to Earth's celestial equator used for the coordinates of poles.

  5. Mystery object lurking past Neptune is baffling astronomers - AOL

    www.aol.com/news/2016-08-12-mystery-object...

    While planets in this solar system rotate around the sun along a similar plane, this one is moving backwards and at a 110-degree angle. Mystery object lurking past Neptune is baffling astronomers ...

  6. Axial tilt - Wikipedia

    en.wikipedia.org/wiki/Axial_tilt

    The axial tilt is defined as the angle between the direction of the positive pole and the normal to the orbital plane. The angles for Earth, Uranus, and Venus are approximately 23°, 97°, and 177° respectively. In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is ...

  7. Moons of Neptune - Wikipedia

    en.wikipedia.org/wiki/Moons_of_Neptune

    In order of distance from Neptune, the regular moons are Naiad, Thalassa, Despina, Galatea, Larissa, Hippocamp, and Proteus. All but the outer two are within Neptune- synchronous orbit (Neptune's rotational period is 0.6713 day or 16 hours [20]) and thus are being tidally decelerated. Naiad, the closest regular moon, is also the second smallest ...

  8. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Mercury's sidereal day is about two-thirds of its orbital period, so by the prograde formula its solar day lasts for two revolutions around the Sun – three times as long as its sidereal day. Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the ...

  9. Outline of Neptune - Wikipedia

    en.wikipedia.org/wiki/Outline_of_Neptune

    Outline of Neptune. The following outline is provided as an overview of and topical guide to Neptune: Neptune – eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth ...