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Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon Decrescent Symbol (bold)
The Moon is Earth's only natural satellite. It is the List of natural satellites, fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia (continent), Australia). The Moon is a planetary-mass object with a planetary differentiation, differentiated Terrestrial planet, rocky body, making it a satellite planet under the geophysical definition of planet, geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant Atmosphere of the Moon, atmosphere, hydrosphere, or Magnetic field of the Moon, magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io (moon), Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an lunar distance (astronomy), average distance of , or about 30 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Full Moon
The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic longitudes of the Sun and Moon differ by 180°). This means that the lunar hemisphere facing Earth—the near side—is completely sunlit and appears as an approximately circular disk. The full moon occurs roughly once a month. The time interval between a full moon and the next repetition of the same phase, a synodic month, averages about 29.53 days. Therefore, in those lunar calendars in which each month begins on the day of the new moon, the full moon falls on either the 14th or 15th day of the lunar month. Because a calendar month consists of a whole number of days, a month in a lunar calendar may be either 29 or 30 days long. Characteristics A full moon is often thought of as an event of a full night's duration, although its phase seen from Earth continuously waxes or wanes, and is fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near Side Of The Moon
The near side of the Moon is the lunar hemisphere that always faces towards Earth, opposite to the far side of the Moon, far side. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth—a situation 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 earthlight (astronomy), earthshine, which is indirect sunlight reflected from the surface of Earth and onto the Moon. Since the orbit of the Moon, Moon's orbit is both somewhat elliptic orbit, elliptical and orbital inclination, inclined to its equator, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Locking
Tidal locking between a pair of co-orbiting 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 the Earth, although there is some variability because the Moon's orbit is not perfectly circular. Usually, only the 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. Alternative names for the tidal locking process are gravitational locking, captured rotation, and spin–orbit locking. The effect arises between two bodies when their gravitational interaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selene
In ancient Greek mythology and religion, Selene (; grc-gre, Σελήνη , meaning "Moon"'' A Greek–English Lexicon's.v. σελήνη) is the goddess and the personification of the Moon. Also known as Mene, she is traditionally the daughter of the Titans Hyperion and Theia, and sister of the sun god Helios and the dawn goddess Eos. She drives her moon chariot across the heavens. Several lovers are attributed to her in various myths, including Zeus, Pan, and the mortal 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 moon and lunar goddesses, but only Selene was regarded as the personification of the Moon itself. Her Roman equivalent is Luna. Names and etymology The name "Selene" is derived from the Greek noun ''selas'' ('), meaning "light, brightness, gleam". In the Doric and Aeolic diale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum ( aphelion) to a minimum ( perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly (see below for several conversions). 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. 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 ast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. 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 background of stars. The ecliptic is an important reference plane and is the basis of the ecliptic coordinate system. Sun's apparent motion The ecliptic is the apparent path of the Sun throughout the course of a year. Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With slightly more than 365 days in one year, the Sun moves a little less than 1° eastward every day. This small difference in the Sun's position against the stars causes any particular spot on Earth's surface to catch up with (and stand directly north or south of) the Sun about four minutes later each day than it would if Earth did not orbit; a day on Earth is therefore 24 ho ... [...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 to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minute And Second Of Arc
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc 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 circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal 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 milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luna
Luna commonly refers to: * Earth's Moon, named "Luna" in Latin * Luna (goddess), the ancient Roman personification of the Moon Luna may also refer to: Places Philippines * Luna, Apayao * Luna, Isabela * Luna, La Union * Luna, San Jose Romania * Luna, Negrești-Oaș town, Satu Mare County * Luna, Cluj * Luna de Jos, Dăbâca Commune, Cluj County * Luna de Sus, Florești, Cluj * Luna River United States * Luna, Arkansas * Luna, Missouri * Luna, Minnesota * Luna, New Mexico * Luna County, New Mexico * Luna Island, in Niagara Falls, New York * Luna Lake (Arizona), a natural body of water * Luna Pier, Michigan, a city Other places * Luna (Etruria), a city in ancient Etruria (now Italy) destroyed by the Arabs in 1016 * Luna, Aragon, Spain * Luna, Rajasthan, India * Luna forest, on the north bank of the Danube, according to Ptolemy * Luna Peak (other) * Roverè della Luna, a commune in Italy * Luna, former name of Louny, a town in the Czech Republic Arts, entert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenian
Selene was the personification of the Moon in Greek mythology. Selene may also refer to: Astronomy * Selene, another name for the Moon of Earth *580 Selene, a minor planet orbiting the sun Animals * ''Selene'' (fish), a genus of fishes in the family Carangidae * ''Actias selene'', a species of moth Characters * Selene (''Underworld''), a character in the film ''Underworld'' *Selene (comics), a Marvel Comics supervillain * Selene, an alias used by Lanfear in Robert Jordan's ''Wheel of Time'' series * Adam Selene, a character in Robert Heinlein's ''The Moon Is a Harsh Mistress'' *Selene (Cro character), fictional sabre-toothed tiger in TV series ''Cro'' * Selene Lindstrom, a character in Isaac Asimov's novel ''The Gods Themselves'' Music * ''Selene'', an album by musician Max Tannone * ''Selene'', a song in Imagine Dragons' album Night Visions *''My Selene'', a song by Finnish power metal band Sonata Arctica in the album Reckoning Night People *Selene (given na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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