It has been established that the phonetic and cultural link between the planet Saturn, Saturday and the Sabbath day is of ancient Mesopotamian origin[8]. Beside the traces of human activity on the Moon, there have been some intended permanent installations like the Moon Museum art piece, Apollo 11 goodwill messages, Lunar plaque, Fallen Astronaut memorial and other artifacts. [198] An estimated 500 million people worldwide watched the transmission by the Apollo TV camera, the largest television audience for a live broadcast at that time. In November 2011, the LRO passed over the large and bright crater Aristarchus. The Cold War-inspired Space Race between the Soviet Union and the U.S. led to an acceleration of interest in exploration of the Moon. or M The day of the week that comes after Sunday and before Tuesday. Tally sticks, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon. The orientation of the Moon's crescent also depends on the latitude of the viewing location; an observer in the tropics can see a smile-shaped crescent Moon. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. Luna 24 was the last Soviet mission to the Moon. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. Because of libration, slightly more than half (about 59%) of the total lunar surface can be viewed from Earth. [160] Since the Moon is orbiting the Earth in the same direction of the Earth's rotation, the high tides occur about every 12 hours and 25 minutes; the 25 minutes is due to the Moon's time to orbit the Earth. All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. As a result, there are two high tides, and two low tides in about 24 hours. This was the first lunar soft landing since Luna 24 in 1976, and the first lunar rover mission since Lunokhod 2 in 1973. In 2016, planetary scientists using data collected on the much earlier NASA Lunar Prospector mission, found two hydrogen-rich areas (most likely former water ice) on opposite sides of the Moon. For example, the plane of the Moon's orbit gradually rotates once every 18.61 years,[138] which affects other aspects of lunar motion. [118], The Moon has an external magnetic field of generally less than 0.2 nanoteslas,[119] or less than one hundred thousandth that of Earth. For many years, the Moon has been recognized as an excellent site for telescopes. [72] The cumulative effects of stress built up by these tidal forces produces moonquakes. [221] 2 ", United Nations Office for Outer Space Affairs, "How many States have signed and ratified the five international treaties governing outer space? Scale model of the Earth–Moon system: Sizes and distances are to scale. The Didache warned early Christians not to fast on Mondays to avoid Judaizing, and suggests Wednesdays instead. n. Abbr. https://www.thefreedictionary.com/Moon+Day. [183] Shen Kuo (1031–1095) of the Song dynasty created an allegory equating the waxing and waning of the Moon to a round ball of reflective silver that, when doused with white powder and viewed from the side, would appear to be a crescent. The Moon's average orbital distance is 384,402 km (238,856 mi),[16][17] or 1.28 light-seconds. Similarly, there are places that remain in permanent shadow at the bottoms of many polar craters,[101] and these "craters of eternal darkness" are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F)[136] and just 26 K (−247 °C; −413 °F) close to the winter solstice in the north polar crater Hermite. ≈ The 1979 Moon Agreement was created to restrict the exploitation of the Moon's resources by any single nation, but as of November 2016, it has been signed and ratified by only 18 nations, none of which engages in self-launched human space exploration or has plans to do so. [207] In 1994, the U.S. sent the joint Defense Department/NASA spacecraft Clementine to lunar orbit. Privately funded lunar exploration has been promoted by the Google Lunar X Prize, announced 13 September 2007, which offers US$20 million to anyone who can land a robotic rover on the Moon and meet other specified criteria. Atomic clocks also show that Earth's day lengthens by about 15 microseconds every year,[165] slowly increasing the rate at which UTC is adjusted by leap seconds. Since the 1972 Apollo 17 mission, the Moon has been visited only by un-crewed spacecraft. Many businesses[who?] [188], In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his book Sidereus Nuncius and noted that it was not smooth but had mountains and craters. [189] Lunar craters, first noted by Galileo, were thought to be volcanic until the 1870s proposal of Richard Proctor that they were formed by collisions. [252] The ancient Sumerians believed that the Moon was the god Nanna,[253][254] who was the father of Inanna, the goddess of the planet Venus,[253][254] and Utu, the god of the sun. ", "Recent gravity models as a result of the Lunar Prospector mission", "Magnetometer / Electron Reflectometer Results", "LADEE - Lunar Atmosphere Dust and Environment Explorer", "Chapter 5, Appendix J: Impact Upon Lunar Atmosphere", "Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data", "NASA's LADEE Spacecraft Finds Neon in Lunar Atmosphere", "Lopsided Cloud of Dust Discovered Around the Moon", "NASA: The Moon Once Had an Atmosphere That Faded Away", "Temperature on the Moon – Surface Temperature of the Moon – PlanetFacts.org", "Global influences of the 18.61 year nodal cycle and 8.85 year cycle of lunar perigee on high tidal levels", "Is the Moon seen as a crescent (and not a "boat") all over the world? The Moon is an astronomical body orbiting Earth and is the planet's only natural satellite. This is supported by the location of the largest crustal magnetizations situated near the antipodes of the giant impact basins. [255][256] The star and crescent arrangement also goes back to the Bronze Age, representing either the Sun and Moon, or the Moon and planet Venus, in combination. The surface area of the Moon is slightly less than the areas of North and South America combined. [199][200] The Apollo missions 11 to 17 (except Apollo 13, which aborted its planned lunar landing) removed 380.05 kilograms (837.87 lb) of lunar rock and soil in 2,196 separate samples. [1], Consistent with this perspective, geochemical mapping made from orbit suggests the crust of mostly anorthosite. [206], After the first Moon race there were years of near quietude but starting in the 1990s, many more countries have become involved in direct exploration of the Moon. [247][248][249], In 2020, U.S. President Donald Trump signed an executive order called "Encouraging International Support for the Recovery and Use of Space Resources". [246] Although several individuals have made claims to the Moon in whole or in part, none of these are considered credible. It is the fifth-largest satellite in the Solar System, and by far[13] the largest among planetary satellites relative to the size of the planet that it orbits. This "drains" angular momentum and rotational kinetic energy from Earth's rotation, slowing the Earth's rotation. [92] The lack of an atmosphere, weather and recent geological processes mean that many of these craters are well-preserved. Thus the distance between Earth and Moon is increasing, and the Earth's rotation is slowing in reaction. A tradition of Ashkenazi Jews to voluntarily fast on the first consecutive Monday Thursday and Monday of the Hebrew month is prevalent among the ultra-orthodox. The main lunar gravity features are mascons, large positive gravitational anomalies associated with some of the giant impact basins, partly caused by the dense mare basaltic lava flows that fill those basins. The Sun has the same tidal effect on the Earth, but its forces of attraction are only 40% that of the Moon's; the Sun's and Moon's interplay is responsible for spring and neap tides. At the 1984 conference at Kona, Hawaii, the giant impact hypothesis emerged as the most consensual theory. It is speculated that these patches were the poles of the Moon billions of years ago before it was tidally locked to Earth.[143]. The cloud is asymmetric, more dense near the boundary between the Moon's dayside and nightside. The U.S. co-launched the Lunar Reconnaissance Orbiter (LRO) and the LCROSS impactor and follow-up observation orbiter on 18 June 2009; LCROSS completed its mission by making a planned and widely observed impact in the crater Cabeus on 9 October 2009,[218] whereas LRO is currently in operation, obtaining precise lunar altimetry and high-resolution imagery. [54], The Moon is a differentiated body. There are estimated to be roughly 300,000 craters wider than 1 km (0.6 mi) on the Moon's near side alone. This atmosphere, sourced from gases ejected from lunar volcanic eruptions, was twice the thickness of that of present-day Mars. [2], Many languages use terms either directly derived from these names, or loan-translations based on them. [59][74][75] Most of the Moon's mare basalts erupted during the Imbrian period, 3.0–3.5 billion years ago, although some radiometrically dated samples are as old as 4.2 billion years. [223], NASA began to plan to resume human missions following the call by U.S. President George W. Bush on 14 January 2004 for a human mission to the Moon by 2019 and the construction of a lunar base by 2024. ⁡ The Moon does not currently have a global dipolar magnetic field and only has crustal magnetization likely acquired early in its history when a dynamo was still operating. [85][86], The lighter-colored regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. [151][152][153] At lower levels, the human perception of reduced brightness as a percentage is provided by the following formula:[154][155], When the actual reduction is 1.00 / 1.30, or about 0.770, the perceived reduction is about 0.877, or 1.00 / 1.14. [164] [230], In 2007, the X Prize Foundation together with Google launched the Google Lunar X Prize to encourage commercial endeavors to the Moon. [128][129] The absence of such neutral species (atoms or molecules) as oxygen, nitrogen, carbon, hydrogen and magnesium, which are present in the regolith, is not understood. Between 4 October 2007 and 10 June 2009, the Japan Aerospace Exploration Agency's Kaguya (Selene) mission, a lunar orbiter fitted with a high-definition video camera, and two small radio-transmitter satellites, obtained lunar geophysics data and took the first high-definition movies from beyond Earth orbit. Philosophers Aristotle and Pliny the Elder argued that the full moon induced insanity in susceptible individuals, believing that the brain, which is mostly water, must be affected by the Moon and its power over the tides, but the Moon's gravity is too slight to affect any single person. [f] The Moon is, after Jupiter's satellite Io, the second-densest satellite in the Solar System among those whose densities are known. the second day of the week; first day of the working week. [197], Neil Armstrong became the first person to walk on the Moon as the commander of the American mission Apollo 11 by first setting foot on the Moon at 02:56 UTC on 21 July 1969. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm. [56][57] This structure is thought to have developed through the fractional crystallization of a global magma ocean shortly after the Moon's formation 4.5 billion years ago. In 499 AD, the Indian astronomer Aryabhata mentioned in his Aryabhatiya that reflected sunlight is the cause of the shining of the Moon.