Misplaced Pages

#46953

87-509: Lunar regolith is the unconsolidated material found on the surface of the Moon and in the Moon's tenuous atmosphere . Sometimes referred to as Lunar soil, Lunar soil specifically refers to the component of regolith smaller than 1 cm. It differs substantially in properties from terrestrial soil . As the Moon's fine surface layer, lunar regolith is picked up by even weak natural phenomena active at

174-407: A crater due south of its major crater was identified as "M". The Moon obviously lacks any mean sea level to be used as vertical datum . The USGS 's Lunar Orbiter Laser Altimeter (LOLA), an instrument on NASA's Lunar Reconnaissance Orbiter (LRO), employs a digital elevation model (DEM) that uses the nominal lunar radius of 1,737.4 km (1,079.6 mi). The selenoid (the geoid for

261-409: A cushion that transmits the pressure from the flow of the solar wind and the barrier of the magnetic field from the object. The magnetopause is the area of the magnetosphere wherein the pressure from the planetary magnetic field is balanced with the pressure from the solar wind. It is the convergence of the shocked solar wind from the magnetosheath with the magnetic field of the object and plasma from

348-482: A definite determination of the source of the problem, as LEAM operated only briefly before the Apollo program ended. It is possible that these storms have been spotted from Earth: For centuries, there have been reports of strange glowing lights on the Moon, known as " transient lunar phenomena " or TLPs. Some TLPs have been observed as momentary flashes, now generally accepted to be visible evidence of meteoroids impacting

435-475: A difference of ratio of mineral phases. The primary minerals identified in Lunar regolith are plagioclase , olivine , augite , orthopyroxene , pigeonite , ilmenite , chromite , quartz , cristobalite , and whitlockite . Glass is abundant in the Lunar regolith and forms as a result of impact melting. Ice is an important mineral in permanently shaded craters. Lunar regolith is divided into highland and mare on

522-462: A distance of approximately 65,000 kilometers (40,000 mi). Earth's bow shock is about 17 kilometers (11 mi) thick and located about 90,000 kilometers (56,000 mi) from Earth. The magnetopause exists at a distance of several hundred kilometers above Earth's surface. Earth's magnetopause has been compared to a sieve because it allows solar wind particles to enter. Kelvin–Helmholtz instabilities occur when large swirls of plasma travel along

609-400: A human Mars expedition, and ranked "dust" as the number one challenge. The report urged study of its mechanical properties, corrosiveness, grittiness, and effect on electrical systems. Most scientists think the only way to answer the questions definitively is by returning samples of Martian dirt and rock to Earth well before launching any astronauts. Although that report addressed Martian dust,

696-591: A result long-term space missions could require complicated and expensive efforts to provide food, such as importing Earth soil , chemically treating lunar regolith to remove heavy metals and oxidize iron atoms, and selectively breeding strains of plants that are adapted to the inhospitable lunar regolith. Therefore lunar regolith has been tested, successfully growing plants from it in a laboratory on Earth. The Apollo astronauts brought back some 360 kilograms (790 lb) of lunar rocks from six landing sites. Although this material has been isolated in vacuum-packed bottles, it

783-403: A tenuous layer of moving dust particles constantly leaping up from and falling back to the Moon's surface, giving rise to a "dust atmosphere" that looks static but is composed of dust particles in constant motion. The term "Moon fountain" has been used to describe this effect by analogy with the stream of molecules of water in a fountain following a ballistic trajectory while appearing static due to

870-454: Is because lunar dust is more chemically reactive and has larger surface areas composed of sharper jagged edges than Earth dust. If the chemically reactive particles are deposited in the lungs, they may cause respiratory disease. Long-term exposure to the dust may cause a more serious respiratory disease similar to silicosis . During lunar exploration the astronauts' spacesuits will become contaminated with lunar dust. The dust will be released into

957-494: Is classified as "induced" when R C F ≪ R P {\displaystyle R_{\rm {CF}}\ll R_{\rm {P}}} , or when the solar wind is not opposed by the object's magnetic field. In this case, the solar wind interacts with the atmosphere or ionosphere of the planet (or surface of the planet, if the planet has no atmosphere). Venus has an induced magnetic field, which means that because Venus appears to have no internal dynamo effect ,

SECTION 10

#1732794018047

1044-447: Is composed of various types of particles including rock fragments, mono-mineralic fragments, and various kinds of glasses including agglutinate particles, volcanic and impact spherules. The agglutinates form at the lunar surface by micrometeorite impacts that cause small-scale melting which fuses adjacent materials together with tiny specks of elemental iron embedded in each dust particle's glassy shell. There are two primary differences in

1131-489: Is created by a celestial body with an active interior dynamo . In the space environment close to a planetary body with a dipole magnetic field such as Earth, the field lines resemble a simple magnetic dipole . Farther out, field lines can be significantly distorted by the flow of electrically conducting plasma , as emitted from the Sun (i.e., the solar wind ) or a nearby star. Planets having active magnetospheres, like

1218-477: Is gone. The chemical and electrostatic properties of the dirt no longer match what future astronauts will encounter on the Moon. Moon dust-contaminated items finally became available to the public in 2014, when the US government approved the sale of private material owned, and collected, by astronauts. Since then only one item has been produced for sale with genuine Moon dust collected after the item spent over 32 hours on

1305-401: Is now unusable for detailed chemical or mechanical analysis—the gritty particles deteriorated the knife-edge indium seals of the vacuum bottles; air has slowly leaked in. Every sample brought back from the Moon has been contaminated by Earth's air and humidity. The dust has acquired a patina of rust, and, as a result of bonding with terrestrial water and oxygen molecules, its chemical reactivity

1392-532: Is the largest planetary magnetosphere in the Solar System, extending up to 7,000,000 kilometers (4,300,000 mi) on the dayside and almost to the orbit of Saturn on the nightside. Jupiter's magnetosphere is stronger than Earth's by an order of magnitude , and its magnetic moment is approximately 18,000 times larger. Venus , Mars , and Pluto , on the other hand, have no magnetic field. This may have had significant effects on their geological history. It

1479-440: Is the primary source of the polar aurora . Also, NASA scientists have suggested that Earth's magnetotail might cause "dust storms" on the Moon by creating a potential difference between the day side and the night side. Many astronomical objects generate and maintain magnetospheres. In the Solar System this includes the Sun, Mercury , Earth , Jupiter , Saturn , Uranus , Neptune , and Ganymede . The magnetosphere of Jupiter

1566-420: Is theorized that Venus and Mars may have lost their primordial water to photodissociation and the solar wind. A strong magnetosphere greatly slows this process. Magnetospheres generated by exoplanets are thought to be common, though the first discoveries did not come until the 2010s. In 2014, a magnetic field around HD 209458 b was inferred from the way hydrogen was evaporating from the planet. In 2019,

1653-416: Is to land Chinese astronauts on the Moon between 2030 and 2039. Selenography The idea that the Moon is not perfectly smooth originates to at least c.  450 BC , when Democritus asserted that the Moon's "lofty mountains and hollow valleys" were the cause of its markings. However, not until the end of the 15th century AD did serious selenography begin. Around AD 1603, William Gilbert made

1740-528: Is used even today. The lunar illustrations in the Almagestum novum were drawn by a fellow Jesuit educator named Francesco Grimaldi, SJ . The nomenclature was based on a subdivision of the visible lunar surface into octants that were numbered in Roman style from I to VIII. Octant I referenced the northwest section and subsequent octants proceeded clockwise in alignment with compass directions. Thus Octant VI

1827-794: The Selenographia was the standard reference on selenography for over a century. Giambattista Riccioli , SJ , a Catholic priest and scholar who lived in northern Italy authored the present scheme of Latin lunar nomenclature. His Almagestum novum was published in 1651 as summary of then current astronomical thinking and recent developments. In particular he outlined the arguments in favor of and against various cosmological models, both heliocentric and geocentric. Almagestum Novum contained scientific reference matter based on contemporary knowledge, and contemporary educators across Europe widely used it. Although this handbook of astronomy has long since been superseded, its system of lunar nomenclature

SECTION 20

#1732794018047

1914-656: The Soviet spacecraft Luna 3 transmitted the first photographs of the far side of the Moon , giving the first view of it in history. The United States launched the Ranger spacecraft between 1961 and 1965 to photograph the lunar surface until the instant they impacted it, the Lunar Orbiters between 1966 and 1967 to photograph the Moon from orbit, and the Surveyors between 1966 and 1968 to photograph and softly land on

2001-403: The maria Imbrium , Serenitatis , Crisium , Smythii , and Orientale , also possess regionally low elevations and elevated rims . Another distinguishing feature of the Moon's shape is that the elevations are on average about 1.9  km higher on the far side than the near side. If it is assumed that the crust is in isostatic equilibrium , and that the density of the crust is everywhere

2088-622: The "ancients," as a gesture to the Catholic Church . Many craters around the Mare Nectaris were denominated in honor of Catholic saints pursuant to the nomenclature of Van Langren. All of them were, however, connected in some mode with astronomy . Later cartographs (maps) removed the "St." from their toponyms . The lunar nomenclature of Giambattista Riccioli was widely used after the publication of his Almagestum Novum , and many of its toponyms are presently used. The system

2175-484: The Earth's crust. In the case of the regolith, this is due in part to the constant bombardment of the lunar surface with protons from the solar wind. One consequence is that iron on the Moon is found in the elemental (0) and cationic (+2) oxidation states, whereas on Earth iron is found primarily in the +2 and +3 oxidation states. A 2005 NASA study listed 20 risks that required further study before humans should commit to

2262-420: The Earth, are capable of mitigating or blocking the effects of solar radiation or cosmic radiation ; in Earth's case, this protects living organisms from harm. Interactions of particles and atmospheres with magnetospheres are studied under the specialized scientific subjects of plasma physics , space physics , and aeronomy . Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that

2349-410: The Moon . Lunar regolith is primarily the result of mechanical weathering . Continual meteoric impacts and bombardment by solar and interstellar charged atomic particles of the lunar surface over billions of years ground the basaltic and anorthositic rock, the regolith of the Moon, into progressively finer material. This situation contrasts fundamentally to terrestrial soil formation, mediated by

2436-477: The Moon's surface called LEAM , short for Lunar Ejecta and Meteorites. It was designed to look for dust kicked up by small meteoroids hitting the Moon's surface. It had three sensors that could record the speed, energy, and direction of tiny particles: one each pointing up, east, and west. LEAM saw a large number of particles every morning, mostly coming from the east or west—rather than above or below—and mostly slower than speeds expected for lunar ejecta. In addition,

2523-450: The Moon's surface, allowing it to be part of the Moon's scant atmosphere. It is easily disturbed and poses a significant hazard to exposed equipment and human health. The fine lunar regolith is made of sharp and very adhesive particles, with a distinct gunpowder taste and smell. Lunar regolith is prospected as a lunar resource , particularly for lunar in situ utilization , such as a lunar building material and regolith for growing plants on

2610-518: The Moon) has been measured gravimetrically by the GRAIL twin satellites. The following historically notable lunar maps and atlases are arranged in chronological order by publication date. Magnetotail In astronomy and planetary science , a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field . It

2697-464: The Moon. A luggage strap, exposed to the elements of the Moon for 32 hours, a piece of Charles "Pete" Conrad's spacesuit on the Apollo 12 mission, was sold by his estate to a private purchaser at auction. In 2017 lunar regolith collected by Neil Armstrong in 1969 was put up for auction. While many jewelry- and watch-makers claim their product contains "Moon dust", the products only contain pieces of, or dust from, meteorites believed to have originated from

Lunar regolith - Misplaced Pages Continue

2784-552: The Moon. It is the first lunar regolith sample to return to Earth since 1976. China is the third country in the world to have brought such material back to Earth. Chang'e-5 is part of the first phase of the Chinese Lunar Exploration Program . Chang'e 6 collected and returned samples from the far side of the Moon in 2024. There are still two projects left in this phase of the program (Chang'e-7 in 2024 and Chang'e-8 in 2027). The program's second phase

2871-506: The Moon. On 11 September 2020, NASA announced that it is willing to create a market for lunar regolith by calling for proposals to purchase it from commercial suppliers. In May 2022, scientists successfully grew plants using lunar regolith. Thale cress ( Arabidopsis thaliana ) was the first plant to have sprouted and grown on Earth in regolith from another celestial body. On 16 December 2020, China's Chang'e 5 mission returned to Earth with about 2 kilograms of rock and dirt it picked up from

2958-534: The ancient Roman Empire , such as Julius Caesar , Tacitus , and Taruntius . Toward the southern half of the lunar cartograph (map) craters were denominated in honor of scholars, writers, and philosophers of medieval Europe and Arabic regions. The outer extremes of Octants V, VI, and VII, and all of Octant VIII were denominated in honor of contemporaries of Giambattista Riccioli . Features of Octant VIII were also denominated in honor of Copernicus , Kepler , and Galileo . These persons were "banished" to it far from

3045-445: The angle of their location relative to the major crater with which they were associated. A satellite crater located due north of the major crater was identified as "Z". The full 360° circle around the major crater was then subdivided evenly into 24 parts, like a 24-hour clock. Each "hour" angle, running clockwise, was assigned a letter, beginning with "A" at 1 o'clock. The letters "I" and "O" were omitted, resulting in only 24 letters. Thus

3132-455: The atmosphere when the suits are removed. The methods used to mitigate exposure will include providing high air recirculation rates in the airlock, the use of a "Double Shell Spacesuit", the use of dust shields, the use of high–grade magnetic separation, and the use of solar flux to sinter and melt the regolith. Anecdotal reports of human exposures to lunar dust during the Apollo program suggest that lunar dust has toxic properties. After each EVA,

3219-414: The basis of their composition, and further divided into high-, low-, and very low-titanium on the basis of their ilmenite content. The contribution of material from external sources is relatively minor (outside of ray systems ), such that the dirt composition at any given location largely reflects the local bedrock composition. Lunar regolith reportedly taste and smell of spent gunpowder . Lunar regolith

3306-470: The bow shock. The magnetosheath is the region of the magnetosphere between the bow shock and the magnetopause. It is formed mainly from shocked solar wind, though it contains a small amount of plasma from the magnetosphere. It is an area exhibiting high particle energy flux , where the direction and magnitude of the magnetic field varies erratically. This is caused by the collection of solar wind gas that has effectively undergone thermalization . It acts as

3393-403: The chemistry of lunar regolith and dirt from terrestrial materials. The first is that the Moon is very dry. As a result, those minerals with water as part of their structure ( mineral hydration ) such as clay , mica , and amphiboles are absent from the Moon's surface. The second difference is that lunar regolith and crust are chemically reduced , rather than being significantly oxidized like

3480-411: The concerns are equally valid concerning lunar dust. The dust found on the lunar surface could cause harmful effects on any human outpost technology and crew members: The principles of astronautical hygiene should be used to assess the risks of exposure to lunar dust during exploration on the Moon's surface and thereby determine the most appropriate measures to control exposure. These may include removing

3567-463: The constancy of the stream. According to a model proposed in 2005 by the Laboratory for Extraterrestrial Physics at NASA 's Goddard Space Flight Center , this is caused by electrostatic levitation . On the daylit side of the Moon, solar hard ultraviolet and X-ray radiation is energetic enough to knock electrons out of atoms and molecules in the lunar regolith. Positive charges build up until

Lunar regolith - Misplaced Pages Continue

3654-421: The crew modules were heavily contaminated with dust; many astronauts reported coughs, throat irritation, watery eyes, and blurred vision that likely reduced their performance. A flight surgeon exposed to the capsule interiors after recovery developed what appeared to be allergic reactions to lunar dust that worsened after each exposure. The apparent toxic effects of lunar dust were never comprehensively studied after

3741-421: The cutoff at less than 50  μm in diameter, while others put it at less than 10 μm. The major processes involved in the formation of lunar regolith are: These processes continue to change the physical and optical properties of the dirt over time, and it is known as space weathering . In addition, fire fountaining, whereby volcanic lava is lofted and cools into small glass beads before falling back to

3828-531: The day and night areas, resulting in horizontal dust transport—a form of "Moon storm". This effect was anticipated in 1956 by science fiction author Hal Clement in his short story "Dust Rag", published in Astounding Science Fiction . There is some evidence for this effect. In the early 1960s, Surveyor 7 and several prior Surveyor spacecraft that soft-landed on the Moon returned photographs showing an unmistakable twilight glow low over

3915-420: The edge of the magnetosphere at a different velocity from the magnetosphere, causing the plasma to slip past. This results in magnetic reconnection , and as the magnetic field lines break and reconnect, solar wind particles are able to enter the magnetosphere. On Earth's nightside, the magnetic field extends in the magnetotail, which lengthwise exceeds 6,300,000 kilometers (3,900,000 mi). Earth's magnetotail

4002-409: The experiment's temperature increased to near 100 degrees Celsius a few hours after each lunar sunrise, so the unit had to be turned off temporarily because it was overheating. It is speculated that this could have been a result of electrically charged moondust sticking to LEAM, darkening its surface so the experiment package absorbed rather than reflected sunlight. However, scientists were unable to make

4089-408: The first lunar drawing based on naked-eye observation. Others soon followed, and when the telescope was invented, initial drawings of poor accuracy were made, but soon thereafter improved in tandem with optics . In the early 18th century, the librations of the Moon were measured, which revealed that more than half of the lunar surface was visible to observers on Earth. In 1750, Johann Meyer produced

4176-430: The first reliable set of lunar coordinates that permitted astronomers to locate lunar features. Lunar mapping became systematic in 1779 when Johann Schröter began meticulous observation and measurement of lunar topography . In 1834 Johann Heinrich von Mädler published the first large cartograph (map) of the Moon, comprising 4 sheets, and he subsequently published The Universal Selenography . All lunar measurement

4263-568: The highland regions were supplanted on later cartographs (maps). See List of features on the Moon for a complete list. Many of the craters were denominated topically pursuant to the octant in which they were located. Craters in Octants I, II, and III were primarily denominated based on names from ancient Greece , such as Plato , Atlas , and Archimedes . Toward the middle in Octants IV, V, and VI craters were denominated based on names from

4350-572: The idea of the solar wind , with the term 'magnetosphere' being proposed by Thomas Gold in 1959 to explain how the solar wind interacted with the Earth's magnetic field. The later mission of Explorer 12 in 1961 led by the Cahill and Amazeen observation in 1963 of a sudden decrease in magnetic field strength near the noon-time meridian, later was named the magnetopause . By 1983, the International Cometary Explorer observed

4437-616: The late 1940s, rockets were used to study cosmic rays . In 1958, Explorer 1 , the first of the Explorer series of space missions, was launched to study the intensity of cosmic rays above the atmosphere and measure the fluctuations in this activity. This mission observed the existence of the Van Allen radiation belt (located in the inner region of Earth's magnetosphere), with the follow-up Explorer 3 later that year definitively proving its existence. Also during 1958, Eugene Parker proposed

SECTION 50

#1732794018047

4524-448: The letters to satellite craters was originally somewhat haphazard. Letters were typically assigned to craters in order of significance rather than location. Precedence depended on the angle of illumination from the Sun at the time of the telescopic observation, which could change during the lunar day. In many cases the assignments were seemingly random. In a number of cases the satellite crater

4611-580: The lunar horizon persisting after the Sun had set. Moreover, contrary to the expectation of airless conditions with no atmospheric haze, the distant horizon between land and sky did not look razor-sharp. Apollo 17 astronauts orbiting the Moon in 1972 repeatedly saw and sketched what they variously called "bands," "streamers" or "twilight rays" for about 10 seconds before lunar sunrise or lunar sunset. Such rays were also reported by astronauts aboard Apollo 8, 10, and 15. These might have been similar to crepuscular rays on Earth. Apollo 17 also placed an experiment on

4698-420: The lunar nomenclature in the 1960s, but new toponyms were limited to toponyms honoring deceased scientists. After Soviet spacecraft photographed the far side of the Moon, many of the newly discovered features were denominated in honor of Soviet scientists and engineers. The IAU assigned all subsequent new lunar toponyms. Some craters were denominated in honor of space explorers . Johann H. Mädler authored

4785-410: The lunar surface. The Soviet Lunokhods 1 (1970) and 2 (1973) traversed almost 50 km of the lunar surface, making detailed photographs of the lunar surface. The Clementine spacecraft obtained the first nearly global cartograph (map) of the lunar topography , and also multispectral images . Successive missions transmitted photographs of increasing resolution. The Moon has been measured by

4872-430: The lunar surface. But others have appeared as amorphous reddish or whitish glows or even as dusky hazy regions that change shape or disappear over seconds or minutes. These may have been a result of sunlight reflecting from suspended lunar dust. While the Moon has a faint atmosphere, traffic and impacts of human activity on the Moon could cause clouds of lunar regolith to spread far across the Moon, and possibly contaminate

4959-414: The magnetic field is weaker, and the density of charged particles is higher. Over Earth's equator , the magnetic field lines become almost horizontal, then return to reconnect at high latitudes. However, at high altitudes, the magnetic field is significantly distorted by the solar wind and its solar magnetic field. On the dayside of Earth, the magnetic field is significantly compressed by the solar wind to

5046-440: The magnetic field on the surface of Earth resembled that of a terrella , a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory , which attributes Earth's magnetic field to the motion of Earth's iron outer core . Through the use of magnetometers , scientists were able to study the variations in Earth's magnetic field as functions of both time and latitude and longitude. Beginning in

5133-417: The magnetosphere extends far beyond the astronomical object. It contains two lobes, referred to as the northern and southern tail lobes. Magnetic field lines in the northern tail lobe point towards the object while those in the southern tail lobe point away. The tail lobes are almost empty, with few charged particles opposing the flow of the solar wind. The two lobes are separated by a plasma sheet, an area where

5220-456: The magnetosphere. Because both sides of this convergence contain magnetized plasma, the interactions between them are complex. The structure of the magnetopause depends upon the Mach number and beta of the plasma, as well as the magnetic field. The magnetopause changes size and shape as the pressure from the solar wind fluctuates. Opposite the compressed magnetic field is the magnetotail, where

5307-425: The magnetotail, or the distant magnetic field. Magnetospheres are dependent on several variables: the type of astronomical object, the nature of sources of plasma and momentum, the period of the object's spin, the nature of the axis about which the object spins, the axis of the magnetic dipole, and the magnitude and direction of the flow of solar wind . The planetary distance where the magnetosphere can withstand

SECTION 60

#1732794018047

5394-514: The methods of laser altimetry and stereo image analysis , including data obtained during several missions. The most visible topographical feature is the giant far-side South Pole-Aitken basin , which possesses the lowest elevations of the Moon. The highest elevations are found just to the northeast of this basin, and it has been suggested that this area might represent thick ejecta deposits that were emplaced during an oblique South Pole-Aitken basin impact event. Other large impact basins, such as

5481-402: The night side would achieve greater electrical tension differences than the day side, possibly launching dust particles to even higher altitudes. This effect could be further enhanced during the portion of the Moon's orbit where it passes through Earth's magnetotail , part of the magnetic field of the Moon . On the terminator there could be significant horizontal electric fields forming between

5568-471: The nomenclature for satellite craters. The subsidiary craters surrounding a major crater were identified by a letter. These subsidiary craters were usually smaller than the crater with which they were associated, with some exceptions. The craters could be assigned letters "A" through "Z," with "I" omitted. Because the great majority of the toponyms of craters were masculine, the major craters were generically denominated " patronymic " craters. The assignment of

5655-420: The only magnetic field present is that formed by the solar wind's wrapping around the physical obstacle of Venus (see also Venus' induced magnetosphere ). When R C F ≈ R P {\displaystyle R_{\rm {CF}}\approx R_{\rm {P}}} , the planet itself and its magnetic field both contribute. It is possible that Mars is of this type. The bow shock forms

5742-410: The original state of the Moon and its special scientific content. Due to a myriad of meteorite impacts (with speeds in the range of 20 km/s), the lunar surface is covered with a thin layer of dust. The dust is electrically charged and sticks to any surface with which it comes in contact. The density of lunar regolith is about 1.5 g/cm and increases with depth. Other factors which may affect

5829-462: The outermost layer of the magnetosphere; the boundary between the magnetosphere and the ambient medium. For stars, this is usually the boundary between the stellar wind and interstellar medium ; for planets, the speed of the solar wind there decreases as it approaches the magnetopause. Due to interactions with the bow shock, the stellar wind plasma gains a substantial anisotropy , leading to various plasma instabilities upstream and downstream of

5916-465: The presence of molecular oxygen (O 2 ), humidity, atmospheric wind , and a robust array of contributing biological processes. Lunar soil typically refers to only the finer fraction of lunar regolith , which is composed of grains 1 cm in diameter or less, but is often used interchangeably. Lunar dust generally connotes even finer materials than lunar soil . There is no official definition as to what size fraction constitutes "dust"; some place

6003-466: The program, and the concentrations of dust that contaminated the spacecraft are not known. In each case, symptoms resolved within 24 hours, and post-flight pulmonary testing found no permanent impacts in the astronauts. The potential of lunar soil for construction of structures has been proposed at least since the proposal of lunarcrete and increasingly tested. The differences between Earth's soil and lunar soil mean that plants struggle to grow in it. As

6090-595: The properties of lunar regolith include large temperature differentials , the presence of a hard vacuum , and the absence of a significant lunar magnetic field , thereby allowing charged solar wind particles to continuously hit the surface of the Moon. The composition of Lunar regolith reflects the composition of the parent rocks it overlies. Over time, material is mixed both vertically and horizontally (a process known as " gardening ") by impact processes. While mare and highland regolith have distinct compositions, their mineral inventories are very similar, rather expressing

6177-480: The rival work Selenographia , which was the first lunar atlas. Hevelius ignored the nomenclature of Van Langren and instead denominated the lunar topography according to terrestrial features, such that the names of lunar features corresponded to the toponyms of their geographical terrestrial counterparts, especially as the latter were denominated by the ancient Roman and Greek civilizations. This work of Hevelius influenced his contemporary European astronomers, and

6264-455: The same, then the higher elevations would be associated with a thicker crust. Using gravity, topography and seismic data, the crust is thought to be on average about 50 ± 15 km thick, with the far-side crust being on average thicker than the near side by about 15 km. The oldest known illustration of the Moon was found in a passage grave in Knowth , County Meath , Ireland . The tomb

6351-409: The satellite craters an eponym . The International Astronomical Union (IAU) assumed authority to denominate lunar features in 1919. The commission for denominating these features formally adopted the convention of using capital Roman letters to identify craters and valleys. When suitable maps of the far side of the Moon became available by 1966, Ewen Whitaker denominated satellite features based on

6438-468: The seas of crises ("Mare Crisium"), serenity ("Mare Serenitatis"), and fertility ("Mare Fecunditatis"). There were also the seas of rain ("Mare Imbrium"), clouds ("Mare Nubium"), and cold ("Mare Frigoris"). The topographical features between the maria were comparably denominated, but were opposite the toponyms of the maria . Thus there were the lands of sterility ("Terra Sterilitatis"), heat ("Terra Caloris"), and life ("Terra Vitae"). However, these names for

6525-539: The solar wind pressure is called the Chapman–Ferraro distance. This is usefully modeled by the formula wherein R P {\displaystyle R_{\rm {P}}} represents the radius of the planet, B s u r f {\displaystyle B_{\rm {surf}}} represents the magnetic field on the surface of the planet at the equator, and V S W {\displaystyle V_{\rm {SW}}} represents

6612-442: The spacesuit in a three-stage airlock, "vacuuming" the suit with a magnet before removal, and using local exhaust ventilation with a high-efficiency particulate filter to remove dust from the spacecraft's atmosphere. The harmful properties of lunar dust are not well known. Based on studies of dust found on Earth, it is expected that exposure to lunar dust will result in greater risks to health both from acute and chronic exposure. This

6699-462: The strength of the surface magnetic fields of 4 hot Jupiters were estimated and ranged between 20 and 120 gauss compared to Jupiter's surface magnetic field of 4.3 gauss. In 2020, a radio emission in the 14-30 MHz band was detected from the Tau Boötis system, likely associated with cyclotron radiation from the poles of Tau Boötis b a signature of a planetary magnetic field. In 2021

6786-542: The surface features of the Moon, based on telescopic observation, were made by Michael van Langren in 1645. Many of his denominations were distinctly Catholic , denominating craters in honor of Catholic royalty and capes and promontories in honor of Catholic saints . The lunar maria were denominated in Latin for terrestrial seas and oceans. Minor craters were denominated in honor of astronomers, mathematicians, and other famous scholars. In 1647, Johannes Hevelius produced

6873-463: The surface, can create small but important deposits in some locations, such as the orange dirt found at Shorty Crater in the Taurus-Littrow valley by Apollo 17 , and the green glass found at Hadley–Apennine by Apollo 15 . Deposits of volcanic beads are also thought to be the origin of Dark Mantle Deposits (DMD) in other locations around the Moon. There is some evidence that the Moon has

6960-417: The tiniest particles of lunar dust (measuring 1 micrometre and smaller) are repelled from the surface and lofted anywhere from metres to kilometres high, with the smallest particles reaching the highest altitudes. Eventually they fall back toward the surface where the process is repeated. On the night side, the dust is negatively charged by electrons from the solar wind . Indeed, the fountain model suggests that

7047-446: The velocity of the solar wind: A magnetosphere is classified as "intrinsic" when R C F ≫ R P {\displaystyle R_{\rm {CF}}\gg R_{\rm {P}}} , or when the primary opposition to the flow of solar wind is the magnetic field of the object. Mercury , Earth, Jupiter , Ganymede , Saturn , Uranus , and Neptune , for example, exhibit intrinsic magnetospheres. A magnetosphere

7134-647: Was Johann H. Schröter , who published a very detailed cartograph (map) of the Moon in 1791 titled the Selenotopografisches Fragmenten . Schröter's adoption of Riccioli's nomenclature perpetuated it as the universally standard lunar nomenclature. A vote of the International Astronomical Union (IAU) in 1935 established the lunar nomenclature of Riccioli , which included 600 lunar toponyms, as universally official and doctrinal. The IAU later expanded and updated

7221-576: Was carbon dated to 3330–2790 BC. Leonardo da Vinci made and annotated some sketches of the Moon in c. 1500. William Gilbert made a drawing of the Moon in which he denominated a dozen surface features in the late 16th century; it was published posthumously in De Mondo Nostro Sublunari Philosophia Nova . After the invention of the telescope , Thomas Harriot (1609), Galileo Galilei (1609), and Christoph Scheiner (1614) made drawings also. Denominations of

7308-456: Was based on direct observation until March 1840, when J.W. Draper , using a 5-inch reflector, produced a daguerreotype of the Moon and thus introduced photography to astronomy . At first, the images were of very poor quality, but as with the telescope 200 years earlier, their quality rapidly improved. By 1890 lunar photography had become a recognized subdiscipline of astronomy. The 20th century witnessed more advances in selenography. In 1959,

7395-444: Was located closer to a major crater with which it was not associated. To identify the patronymic crater, Mädler placed the identifying letter to the side of the midpoint of the feature that was closest to the associated major crater. This also had the advantage of permitting omission of the toponyms of the major craters from the cartographs (maps) when their subsidiary features were labelled. Over time, lunar observers assigned many of

7482-411: Was scientifically inclusive and was considered eloquent and poetic in style, and therefore it appealed widely to his contemporaries. It was also readily extensible with new toponyms for additional features. Thus it replaced the nomenclature of Van Langren and Hevelius. Later astronomers and lunar cartographers augmented the nomenclature with additional toponyms . The most notable among these contributors

7569-405: Was to the south and included Clavius and Tycho Craters. The Latin nomenclature had two components: the first denominated the broad features of terrae (lands) and maria (seas) and the second denominated the craters. Riccioli authored lunar toponyms derived from the names of various conditions, including climactic ones, whose causes were historically attributed to the Moon. Thus there were

#46953