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Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar day) that is synchronized to its orbital period (Lunar month#Synodic month, lunar month) of 29.5 Earth days. This is the product of Earth's gravitation having tidal forces, tidally pulled on the Moon until one part of it stopped rotating away from the near side of the Moon, near side, making always the same lunar surface face Earth. Conversley, the gravitational pull of the Moon, on Earth, is the main driver of Earth's tides. In geophysical definition of planet, geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is , roughly one-quarter of Earth's (about as wide as the contiguous United States). Within the Solar System, it is the List of Solar System objects by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon Crescent Symbol (bold)
The Moon is Earth's only natural satellite. It orbits around Earth at an average distance of (; about 30 times Earth's diameter). The Moon rotates, with a rotation period (lunar day) that is synchronized to its orbital period (lunar month) of 29.5 Earth days. This is the product of Earth's gravitation having tidally pulled on the Moon until one part of it stopped rotating away from the near side, making always the same lunar surface face Earth. Conversley, the gravitational pull of the Moon, on Earth, is the main driver of Earth's tides. In geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is , roughly one-quarter of Earth's (about as wide as the contiguous United States). Within the Solar System, it is the largest and most massive satellite in relation to its parent planet, the fifth-largest and fifth-most massive moon overall, and larger and more massive than all known dwarf planets. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering Water distribution on Earth, 70.8% of Earth's crust. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation, while large Ice sheet, sheets of ice at Polar regions of Earth, Earth's polar polar desert, deserts retain more water than Earth's groundwater, lakes, rivers, and Water vapor#In Earth's atmosphere, atmospheric water combined. Earth's crust consists of slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's outer core, Earth has a liquid outer core that generates a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near Side Of The Moon
The near side of the Moon is the lunar hemisphere that faces Earth, opposite to the far side. The near side of the Moon has always the same lunar surface (or "face") oriented to Earth, due to the Moon rotating on its axis at the same rate that the Moon orbits the Earth—a phenomenon known as tidal locking. The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases. Sometimes the dark portion of the Moon is faintly visible due to earthshine, which is indirect sunlight reflected from the surface of Earth and onto the Moon. Since the Moon's orbit is both somewhat elliptical and inclined to its equatorial plane, libration allows up to 59% of the Moon's surface to be viewed from Earth (though only half at any moment from any point). Orientation The image of the Moon here is drawn as is normally shown on maps, that is with north on top and west to the left. Astronomers traditionally turn the map to have south on top to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Locking
Tidal locking between a pair of co-orbiting astronomical body, astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked body possesses synchronous rotation, the object takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces Earth, although there is some libration, variability because the Moon's orbit is not perfectly circular. Usually, only the natural satellite, satellite is tidally locked to the larger body. However, if both the difference in mass between the two bodies and the distance between them are relatively small, each may be tidally locked to the other; this is the case for Pluto and Charon (moon), Charon, and for Eris (dwarf planet), Eris and Dysnomia (moon), Dysnomia. Alternative names for the tidal locking process are gravitational locking, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selene
In ancient Greek mythology and Ancient Greek religion, religion, Selene (; , meaning "Moon")''A Greek–English Lexicon's.v. σελήνη is the goddess and personification of the Moon. Also known as Mene (), she is traditionally the daughter of the Titans Hyperion (Titan), Hyperion and Theia, and sister of the Solar deity, sun god Helios and the Dawn deities, dawn goddess Eos. She drives her moon chariot across the heavens. Several lovers are attributed to her in various myths, including Zeus, Pan (god), Pan, and the mortal Endymion (mythology), Endymion. In post-classical times, Selene was often identified with Artemis, much as her brother, Helios, was identified with Apollo. Selene and Artemis were also associated with Hecate and all three were regarded as lunar deity, moon and lunar goddesses, but only Selene was regarded as the personification of the Moon itself. Her equivalent in Roman religion and mythology is the goddess Luna (goddess), Luna. Etymology and origins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Precession
Lunar precession is a term used for three different precession motions related to the Moon. First, it can refer to change in orientation of the lunar rotational axis with respect to a plane of reference, reference plane, following the normal rules of precession followed by spinning objects. In addition, the orbit of the Moon undergoes two further types of precessional motion: apsidal and nodal. Axial precession The rotational axis of the Moon also undergoes precession. Since the Moon's axial tilt is only 1.5° with respect to the ecliptic (the plane of Earth's orbit around the Sun), this effect is small. Once every 18.6 years, the lunar north pole describes a small circle around a point in the constellation Draco (constellation), Draco, while correspondingly, the lunar south pole describes a small circle around a point in the constellation Dorado. Similar to Earth, the Moon's axial precession is westwards - whereas Apsidal precession is in the same direction as the rotation (me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the fixed stars, background of stars – specifically the Zodiac constellations. The planets of the Solar System can also be seen along the ecliptic, because their orbital planes are very close to Earth's. The Moon's orbital plane is also similar to Earth's; the ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. The ecliptic is an important Plane of reference, reference plane and is the basis of the ecliptic coordinate system. Ancient scientists were able to calculate Earth's axial tilt by comparing the ecliptic plane to that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. One au is approximately equivalent to 499 light-seconds. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical unit. In the astronomical literature, the symbol AU is common. In 2006, the International Bureau of Weights and Measures (BIPM) had recommended ua as the symbol for the unit, from the French ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luna (goddess)
In Sabine and ancient Roman religion and myth, Luna is the divine embodiment of the Moon (Latin ''Lūna'' ). She is often presented as the female complement of the Sun, Sol, conceived of as a god. Luna is also sometimes represented as an aspect of the Roman triple goddess (''diva triformis''), along with Diana and either Proserpina or Hecate. ''Luna'' is not always a distinct goddess, but sometimes rather an epithet that specializes a goddess, since both Diana and Juno are identified as moon goddesses. In Roman art, Luna attributes are the crescent moon plus the two-yoke chariot (''biga''). In the '' Carmen Saeculare'', performed in 17 BC, Horace invokes her as the "two-horned queen of the stars" (''siderum regina bicornis''), bidding her to listen to the girls singing as Apollo listens to the boys. Varro categorized Luna and Sol among the visible gods, as distinguished from invisible gods such as Neptune, and deified mortals such as Hercules. She was one of the deities Macr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar North Pole
The lunar north pole is the point in the Northern Hemisphere of the Moon where the lunar axis of rotation meets its surface. The lunar North Pole is the northernmost point on the Moon, lying diametrically opposite the lunar south pole. It defines latitude 90° North. At the lunar north pole all directions point south; all lines of longitude converge there, so its longitude can be defined as any degree value. Craters Notable craters in the lunar north polar region (between 60° North latitude and the North pole) include: Avogadro, Bel'kovich, Brianchon, Emden, Gamow, Goldschmidt, Hermite, J. Herschel, Meton, Nansen, Pascal, Petermann, Philolaus, Plaskett, Pythagoras, Rozhdestvenskiy, Schwarzschild, Seares, Sommerfeld, Stebbins, Sylvester, Thales, Van't Hoff, W. Bond, and Whipple. Exploration The Astrobotic Technology Icebreaker mission was a mission concept planned for a 2015 mission, then delayed to 2016, and then cancelled. It was meant as a competition t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arcminutes
A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth's circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (abbreviated as arcsec), or arc second, denoted by the symbol , is a unit of angular measurement equal to of a minute of arc, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal (base 60) subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
