Check out our other new and used items>>>>>HERE! (click me)
FOR SALE:
An awesome, NASA astronaut-themed lenticular 3D jigsaw puzzle
2020 DISCOVERY "ASTRONAUT" PUZZLE BY PRIME 3D (9" x 6")
DETAILS:
It's the "Last Man on the Moon" in puzzle form!
The Discovery "Astronaut" 50-piece lenticular jigsaw puzzle features a graphic that utilizes an official photograph of a NASA astronuat on the moon during the Apollo 17 mission. Discovery took some artistic liberty by altering the layout and adding more more mesmerizing color and shape to the background. And what makes the puzzle image even more awesome is that Prime 3D Global utilized their high-quality lenticular printing technology to make it "3D" art. The brave NASA moonwalker in the graphic is American astronaut, naval aviator, electrical engineer, aeronautical engineer, and fighter pilot, Gene Cernan. During the last mission of NASA's Apollo program (AKA Project Apollo) Gene Cernan acted as commander and became one of only 12 astronauts ever to walk the moon and he happens to be the last to step off it - earning him the title "The Last Human on the Moon". Prime 3D Global also printed
the beautiful graphic on a separate lenticular card and attached it to
the front of the box to showcase the puzzle's main feature.
This small "3D" art jigsaw puzzle would look great framed!
Hang on a deserving wall or display on a shelf or mantel. Perfect for a space-themed bar or man cave.
A must have for the lenticular art and space fanatic especially those who collect all things NASA!
Brand: Discovery
Title: "Astronaut"Year: 2020
Piece Count: 50
Completed Size: 9 x 6 in. (22.9 x 15.2 cm)
Manufacturer: Prime 3D Global
Country: China
CONDITION:
New in box. Box may have shelf wear. Please see photos.
To ensure safe delivery all items are carefully packaged before shipping out.
THANK YOU FOR LOOKING. QUESTIONS? JUST ASK.
*ALL PHOTOS AND TEXT ARE INTELLECTUAL PROPERTY OF SIDEWAYS STAIRS CO. ALL RIGHTS RESERVED.*
"Eugene Andrew Cernan (/ˈsɜːrnən/; March 14, 1934 – January 16, 2017) was an American astronaut, naval aviator, electrical engineer, aeronautical engineer, and fighter pilot. During the Apollo 17 mission, Cernan became the eleventh human being to walk on the Moon. As he re-entered the Apollo Lunar Module after Harrison Schmitt on their third and final lunar excursion, he remains as of 2023, famously: "The last human on the Moon".
Before becoming an astronaut, Cernan graduated with a Bachelor of Science degree in electrical engineering from Purdue University and joined the U.S. Navy through the Naval Reserve Officers Training Corps (NROTC). After flight training, he received his naval aviator wings and served as a fighter pilot. In 1963, he received a Master of Science degree in aeronautical engineering from the U.S. Naval Postgraduate School. Achieving the rank of captain, he retired from the Navy in 1976.
Cernan traveled into space three times and to the Moon twice: as pilot of Gemini 9A in June 1966, as lunar module pilot of Apollo 10 in May 1969, and as commander of Apollo 17 in December 1972, the final Apollo lunar landing. Cernan was also a backup crew member of the Gemini 12, Apollo 7 and Apollo 14 space missions.
Biography
Early years
Cernan was born on March 14, 1934, in Chicago, Illinois;[1] he was the son of Andrew George Cernan (1904–1967) and Rose Cernan (née Cihlar; 1898–1991). His father was of Slovak descent and his mother was of Czech ancestry. He had one older sister, Dolores Ann (1929–2019).[2][3] Cernan grew up in the Illinois towns of Bellwood and Maywood. He was a Boy Scout and earned the rank of Second Class.[4] After attending McKinley Elementary School in Bellwood, and graduating from Proviso Township High School in Maywood in 1952, he studied at Purdue University where he became a member of the Phi Gamma Delta fraternity, serving as a treasurer. At Purdue, Cernan was also president of the Quarterdeck Society and the Scabbard and Blade, and a member of the Phi Eta Sigma honor society and Tau Beta Pi engineering honor society. He was on the military ball committee and was a member of the Skull and Crescent leadership honor society.[5] After his sophomore year, he accepted a partial Navy ROTC scholarship that required him to serve aboard USS Roanoke between his junior and senior years. In 1956, Cernan received a Bachelor of Science degree in electrical engineering; his final GPA was 5.1 out of 6.0.[6]
Navy service
Cernan was commissioned a U.S. Navy Ensign through the Naval Reserve Officers Training Corps (NROTC) at Purdue, and was initially stationed on the USS Saipan. Cernan changed to active duty and attended flying training at Whiting Field, Florida, Barron Field, Texas, NAS Corpus Christi, Texas, and NAS Memphis, Tennessee.[7]: 29–31 Following flight training on the T-28 Trojan, T-33 Shooting Star, and F9F Panther, Cernan became a Naval Aviator, flying FJ-4 Fury and A-4 Skyhawk jets in Attack Squadrons 126 and 113.[7]: 31–33, 38–39 Upon completion of his assignment in NAS Miramar, California, he finished his education in 1963 at the U.S. Naval Postgraduate School with a Master of Science degree in aeronautical engineering.[8]
During his naval career, Cernan logged more than 5,000 hours of flying time, including 4,800 hours in jet aircraft. Cernan also made at least 200 successful landings on aircraft carriers.[8]
NASA career
In October 1963, NASA selected Cernan as one of the third group of astronauts to participate in the Gemini and Apollo space programs.[8]
Gemini program
Main article: Gemini 9A
Cernan aboard Gemini 9A
Cernan was originally selected with Thomas Stafford as backup pilot for Gemini 9. When the prime crew of Elliot See and Charles Bassett was killed in the crash of NASA T-38A "901" (USAF serial 63–8181) at Lambert Field, Missouri, on February 28, 1966, the backup crew became the prime crew—the first time in NASA history this happened.[9] Gemini 9A encountered a number of problems; the original target vehicle exploded during launch and the planned docking with a substitute target vehicle was made impossible by the failure of a protective shroud to separate after launch.[9] The crew, however, performed a rendezvous that simulated procedures that would be used in the Apollo 10 mission; the first optical rendezvous and a lunar-orbit-abort rendezvous. Cernan performed the second American EVA, the third-ever spacewalk, but overexertion caused by a lack of limb restraints prevented testing of the Astronaut Maneuvering Unit and forced the early termination of the spacewalk.[9] Cernan was also a backup pilot for the Gemini 12 mission.[10]
Apollo program
Main articles: Apollo 10 and Apollo 17
Cernan and Snoopy during Apollo 10 press conference
Cernan in the LM after EVA 3 on Apollo 17
0:30
Astronauts Cernan and Schmitt singing "The Fountain in the Park" on the Moon during the Apollo 17 mission
Cernan at the beginning of EVA 3
The Blue Marble, an iconic photograph of Earth, is credited to the three crewmen of Apollo 17.
Apollo 10
Cernan was selected for the lunar module pilot position on the backup crew for Apollo 7—although that flight carried no lunar module.[11] Standard crew rotation put him in place as the Lunar Module Pilot on Apollo 10—the final dress rehearsal mission for the first Apollo lunar landing—on May 18–26, 1969.
During the Apollo 10 mission, Cernan and his commander, Tom Stafford, piloted the Lunar Module Snoopy in lunar orbit to within 8.5 nautical miles (15.7 km) of the lunar surface, and successfully executed every phase of a lunar landing up to final powered descent. This provided NASA planners with critical knowledge of technical systems and lunar gravitational conditions to enable Apollo 11 to land on the Moon two months later. Apollo 10 holds the record for the highest speed attained by any crewed vehicle at 39,897 km/h (24,791 mph) – more than 11km per second — during its return from the Moon on May 26, 1969.[10]
Apollo 17
Cernan turned down the opportunity to walk on the Moon as Lunar Module Pilot of Apollo 16, preferring to risk missing a flight for the opportunity to command his own mission.[12] Cernan moved back into the Apollo rotation as commander of the backup crew of Cernan, Ronald E. Evans, and Joe Engle for Apollo 14, putting him in position through normal crew rotation to command his own crew on Apollo 17. Escalating budget cutbacks for NASA, however, brought the number of future lunar missions into question. After the cancellation of Apollo 15 in its original H class profile and Apollo 19 in September 1970, pressure from the scientific community to shift Harrison Schmitt, the sole professional geologist in the active Apollo roster of astronauts, to the crew of Apollo 17, the final scheduled Apollo mission, mounted. In August 1971, NASA named Schmitt as the lunar module pilot for Apollo 17, which meant the original LM pilot Joe Engle never had the opportunity to walk on the Moon. Cernan fought to keep his crew together; given the choice of flying with Schmitt as LMP or seeing his entire crew removed from Apollo 17, Cernan chose to fly with Schmitt. Cernan eventually came to have a positive evaluation of Schmitt's abilities; he concluded that Schmitt was an outstanding LM pilot while Engle—notwithstanding his outstanding record as an aircraft test pilot—was merely an adequate one.[13]
Cernan's role as commander of Apollo 17 closed out the Apollo program's lunar exploration mission with a number of record-setting achievements. During the three days of Apollo 17's surface activity (Dec. 11–14, 1972), Cernan and Schmitt performed three EVAs for a total of about 22 hours of exploration of the Taurus–Littrow valley. Their first EVA alone was more than three times the length astronauts Neil Armstrong and Buzz Aldrin spent outside the LM on Apollo 11. During this time Cernan and Schmitt covered more than 35 km (22 mi) using the Lunar Roving Vehicle and spent a great deal of time collecting geologic samples (including a record 34 kilograms (75 lb) of samples, the most of any Apollo mission) that would shed light on the Moon's early history. Cernan piloted the rover on its final sortie, recording a maximum speed of 11.2 mph (18.0 km/h), giving him the unofficial lunar land speed record.[14]
As Cernan prepared to climb the ladder for the final time, he spoke these words, currently the last spoken by a human being standing on the lunar surface:
Bob, this is Gene, and I'm on the surface; and, as I take man's last step from the surface, back home for some time to come—but we believe not too long into the future—I'd like to just (say) what I believe history will record: that America's challenge of today has forged man's destiny of tomorrow. And, as we leave the Moon at Taurus–Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind. Godspeed the crew of Apollo 17.
— Cernan, [15]
Cernan's status as the last person to walk on the Moon means Purdue University is the alma mater of both the first person to walk on the Moon—Neil Armstrong—and the most recent. Cernan is one of only three astronauts to travel to the Moon on two occasions; the others being Jim Lovell and John Young. He is also one of only twelve people to have walked on the Moon.
Post-NASA activities
Eugene Cernan at a memorial service for Neil Armstrong September 13, 2012
In 1976, Cernan retired from the Navy with the rank of captain and went from NASA into private business, becoming Executive Vice President of Coral Petroleum Inc. before starting his own company, The Cernan Corporation, in 1981.[8] In 1981 and 1982, Cernan joined Frank Reynolds and Jules Bergman on the extensive ABC coverage of the first 3 Space Shuttle launches. Many hours of these ABC broadcasts have been uploaded to YouTube in recent years. From 1987 he was a contributor to ABC News and the weekly segment of its Good Morning America program titled "Breakthrough", which covered health, science, and medicine.[16]
In 1999, with co-author Donald A. Davis, he published his memoir The Last Man on the Moon, which is about his naval and NASA career. He is featured in the space exploration documentary In the Shadow of the Moon in which he said, "truth needs no defense" and "nobody can take those footsteps I made on the surface of the Moon away from me".[17] Cernan also contributed to the book of the same name.
Cernan and Neil Armstrong testified before U.S. Congress in 2010 in opposition to the cancellation of the Constellation program, which had been initiated during the George W. Bush administration as part of the Vision for Space Exploration with the aim of returning humans to the Moon and eventually Mars, but was deemed underfunded and unsustainable by the Augustine Commission in 2009.[18]
Cernan paired his criticism of the cancellation of Constellation with expressions of skepticism about Commercial Resupply Services (CRS) and Commercial Crew Development (CCDev), NASA's planned replacements for that program's role in supplying cargo and crew to the International Space Station. Such companies, Cernan warned, "do not yet know what they don't know." Cernan's view of commercial space companies—in particular SpaceX, which participates in both programs—underwent a positive shift after being debriefed by SpaceX venture capitalist Steve Jurvetson as part of his effort to obtain the signatures of nine Apollo astronauts on a photograph meant as a gift to SpaceX founder Elon Musk to commemorate the first successful SpaceX cargo mission to the ISS in 2012. Eventually, Cernan was won over and signed the photograph; "As I told him these stories of heroic entrepreneurship, I could see his mind turning." Jurvetson wrote; "He found a reconciliation: 'I never read any of this in the news. Why doesn't the press report on this?'" [19]
Cernan gave a eulogy at Armstrong's funeral in 2012.[20][21]
In 2014, Cernan appeared in the documentary The Last Man on the Moon, made by British filmmaker Mark Craig and based on Cernan's 1999 memoir of the same title.[22] The film received the Texas Independent Film Award from Houston Film Critics Society and the Movies for Grownups Award from AARP The Magazine.[23][24]
Personal life
Cernan was married twice and had one daughter. His first wife was Barbara Jean Atchley, a flight attendant for Continental Airlines, whom he married in 1961. They had one daughter, Tracy (born in 1963). The couple separated in 1980 and divorced in 1981. They remained friends.[25] His second marriage was to Janis Ellen "Nanna" Cernan (née Jones; 1939–2021), which lasted for nearly 30 years from 1987 until his death. Cernan gained two step-daughters, Kelly and Danielle.[26]
Death
Cernan died in a hospital in Houston on January 16, 2017, at the age of 82.[27] His funeral was held at St. Martin's Episcopal Church in Houston.[28] He was buried with full military honors at Texas State Cemetery, the first astronaut to be buried there, in a private service on January 25, 2017.[29][30]
Organizations
Cernan was a member of several organizations, including Fellow, American Astronautical Society; member, Society of Experimental Test Pilots; member, Tau Beta Pi (National Engineering Society), Sigma Xi (National Science Research Society), Phi Gamma Delta (National Social Fraternity), and The Explorers Club.[8]
Awards and honors
Naval Aviator Astronaut Insignia[8]
Navy Distinguished Service Medal, Gold star device in lieu of second award[8]
Distinguished Flying Cross[8]
National Defense Service Medal
NASA Distinguished Service Medal[8]
NASA Exceptional Service Medal[8]
Wright Brothers Memorial Trophy, 2007[31]
U.S. Astronaut Hall of Fame[32][33]
Slovakia: Grand Officer (or 2nd Class) of the Order of the White Double Cross (September 25, 1994).[34]
Great American Award, The All-American Boys Chorus, 2014.[35]
Cernan was inducted into the International Air & Space Hall of Fame at the San Diego Air & Space Museum in 2007.[36]
Orbital ATK announced the naming of its Cygnus CRS OA-8E Cargo Delivery Spacecraft the S.S. Gene Cernan in honor of Cernan in October 2017.[37] The S.S. Gene Cernan successfully launched to the International Space Station on November 12, 2017.[38]
In 2000, Eugene Cernan was inducted into the National Aviation Hall of Fame.[39]
Cernan, along with nine of his Gemini astronaut colleagues, was inducted into the International Space Hall of Fame in 1982.[10][40]
In popular culture
Cernan's lunar space suit on display at the National Air and Space Museum in Washington, D.C.
On July 2, 1974, Cernan was a roaster of Don Rickles on The Dean Martin Celebrity Roast. At the end of the roast, Rickles—who attended the Apollo 17 launch—paid tribute to Cernan as a "delightful, wonderful, great hero".[41]
In the 1998 Primetime Emmy Award-winning HBO miniseries From the Earth to the Moon, Cernan was portrayed by Daniel Hugh Kelly.[42]
Cernan was featured in the Discovery Channel's 2008 documentary miniseries When We Left Earth: The NASA Missions, talking about his involvement and missions as an astronaut.[43]
A popular belief is that Cernan wrote his daughter's initials on a rock on the Moon, Tracy's Rock. The story, and Cernan's relationship with his daughter, was later adapted into "Tracy's Song" by pop-rock band No More Kings. The story is inaccurate, as Cernan wrote her initials in the dust, not on a rock. He states in the 2014 documentary The Last Man on the Moon[44] that he wrote them in the lunar dust as he left the rover to return to the LEM and Earth.[45] The true story of leaving the initials on the lunar surface was prominently mentioned in "The Last Walt", a 2012 episode of Modern Family.[46]
A recording of Cernan's voice during the Apollo 17 mission was sampled by Daft Punk for "Contact", the last track on their 2013 album Random Access Memories.[47] Cernan's last words from the lunar surface, along with Lunar Module Pilot Harrison Schmitt's recollections, were used by the band Public Service Broadcasting for the song "Tomorrow", the final track of their 2015 album The Race for Space.[48]
The Apple TV+ show For All Mankind dramatizes the Moon landings. The fictional main character draws comparisons to and shares similarity with the commander of the Apollo 17 mission, Gene Cernan.[" (wikipedia.org)
"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,[f] with a diameter about one-quarter that of Earth (comparable to the width of Australia).[16] 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.[17] It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at 0.1654 g, 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 384,400 km (238,900 mi), 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 synodic period of 29.5 days, the amount of visible surface illuminated by the Sun varies from none up to 100%, resulting in lunar phases that form the basis for the months of a lunar calendar. The Moon is tidally locked to Earth, which means that the length of a full rotation of the Moon on its own axis causes its same side (the near side) to always face Earth, and the somewhat longer lunar day is the same as the synodic period. However, 59% of the total lunar surface can be seen from Earth through cyclical shifts in perspective known as libration.
The most widely accepted origin explanation posits that the Moon formed 4.51 billion years ago, not long after Earth, out of the debris from a giant impact between the planet and a hypothesized Mars-sized body called Theia. It then receded to a wider orbit because of tidal interaction with the Earth. The near side of the Moon is marked by dark volcanic maria ("seas"), which fill the spaces between bright ancient crustal highlands and prominent impact craters. Most of the large impact basins and mare surfaces were in place by the end of the Imbrian period, some three billion years ago. The lunar surface is fairly non-reflective, with the reflectance of lunar soil being comparable to that of asphalt. However, due to its large angular diameter, the full moon is the brightest celestial object in the night sky. The Moon's apparent size is nearly the same as that of the Sun, allowing it to cover the Sun almost completely during a total solar eclipse.
Both the Moon's prominence in Earth's sky and its regular cycle of phases have provided cultural references and influences for human societies throughout history. Such influences can be found in language, calendar systems, art, and mythology. The first artificial object to reach the Moon was the Soviet Union's uncrewed Luna 2 spacecraft in 1959; this was followed by the first successful soft landing by Luna 9 in 1966. The only human lunar missions to date have been those of the United States' Apollo program, which landed twelve men on the surface between 1969 and 1972. These and later uncrewed missions returned lunar rocks that have been used to develop a detailed geological understanding of the Moon's origins, internal structure, and subsequent history. The Moon is the only celestial body visited by humans.
Names and etymology
See also: Moon § Mythology and art
The usual English proper name for Earth's natural satellite is simply Moon, with a capital M.[18][19] The noun moon is derived from Old English mōna, which (like all its Germanic cognates) stems from Proto-Germanic *mēnōn,[20] which in turn comes from Proto-Indo-European *mēnsis "month"[21] (from earlier *mēnōt, genitive *mēneses) which may be related to the verb "measure" (of time).[22]
Occasionally, the name Luna /ˈluːnə/ is used in scientific writing[23] and especially in science fiction to distinguish the Earth's moon from others, while in poetry "Luna" has been used to denote personification of the Moon.[24] Cynthia /ˈsɪnθiə/ is another poetic name, though rare, for the Moon personified as a goddess,[25] while Selene /səˈliːniː/ (literally "Moon") is the Greek goddess of the Moon.
The usual English adjective pertaining to the Moon is "lunar", derived from the Latin word for the Moon, lūna. The adjective selenian /səliːniən/,[26] derived from the Greek word for the Moon, σελήνη selēnē, and used to describe the Moon as a world rather than as an object in the sky, is rare,[27] while its cognate selenic was originally a rare synonym[28] but now nearly always refers to the chemical element selenium.[29] The Greek word for the Moon does however provide us with the prefix seleno-, as in selenography, the study of the physical features of the Moon, as well as the element name selenium.[30][31]
The Greek goddess of the wilderness and the hunt, Artemis, equated with the Roman Diana, one of whose symbols was the Moon and who was often regarded as the goddess of the Moon, was also called Cynthia, from her legendary birthplace on Mount Cynthus.[32] These names – Luna, Cynthia and Selene – are reflected in technical terms for lunar orbits such as apolune, pericynthion and selenocentric.
The astronomical symbol for the Moon is a crescent, ☾, for example in M☾ 'lunar mass' (also ML)....
Atmosphere
Main article: Atmosphere of the Moon
The thin lunar atmosphere is visible on the Moon's surface at sunrise and sunset with the Lunar Horizon Glow[76] and lunar twilight rays, like Earth's crepuscular rays. This Apollo 17 sketch depicts the glow and rays[77] among the general zodiacal light.[78][79]
The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 tonnes (9.8 long tons; 11 short tons).[80] The surface pressure of this small mass is around 3 × 10−15 atm (0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, a product of the bombardment of lunar soil by solar wind ions.[15][81] Elements that have been detected include sodium and potassium, produced by sputtering (also found in the atmospheres of Mercury and Io); helium-4 and neon[82] from the solar wind; and argon-40, radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle.[83][84] 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.[83] Water vapor has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith.[85] These gases either return into the regolith because of the Moon's gravity or are lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field.[83]
Studies of Moon magma samples retrieved by the Apollo missions demonstrate that the Moon had once possessed a relatively thick atmosphere for a period of 70 million years between 3 and 4 billion years ago. This atmosphere, sourced from gases ejected from lunar volcanic eruptions, was twice the thickness of that of present-day Mars. The ancient lunar atmosphere was eventually stripped away by solar winds and dissipated into space.[86]
A permanent Moon dust cloud exists around the Moon, generated by small particles from comets. Estimates are 5 tons of comet particles strike the Moon's surface every 24 hours, resulting in the ejection of dust particles. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising up to 100 kilometers above the surface. Dust counts made by LADEE's Lunar Dust EXperiment (LDEX) found particle counts peaked during the Geminid, Quadrantid, Northern Taurid, and Omicron Centaurid meteor showers, when the Earth, and Moon pass through comet debris. The lunar dust cloud is asymmetric, being more dense near the boundary between the Moon's dayside and nightside.[87][88]
Surface conditions
Gene Cernan with lunar dust stuck on his suit. Lunar dust is highly abrasive and can cause damage to human lungs, nervous, and cardiovascular systems.[89]
Ionizing radiation from cosmic rays, the Sun and the resulting neutron radiation[90] produce radiation levels on average of 1.369 millisieverts per day during lunar daytime,[14] which is about 2.6 times more than on the International Space Station with 0.53 millisieverts per day at about 400 km above Earth in orbit, 5-10 times more than during a trans-Atlantic flight, 200 times more than on Earth's surface.[91] For further comparison radiation on a flight to Mars is about 1.84 millisieverts per day and on Mars on average 0.342, with some locations on Mars possibly having levels as low as 0.64 millisieverts per day.[92][93]
The Moon's axial tilt with respect to the ecliptic is only 1.5427°,[8][94] much less than the 23.44° of Earth. Because of this small tilt, the Moon's solar illumination varies much less with season than on Earth and it allows for the existence of some peaks of eternal light at the Moon's north pole, at the rim of the crater Peary.
The surface is exposed to drastic temperature differences ranging from 140 °C to −171 °C depending on the solar irradiance. Because of the lack of atmosphere, temperatures of different areas vary particularly upon whether they are in sunlight or shadow,[95] making topographical details play a decisive role on local surface temperatures.[96] Parts of many craters, particularly the bottoms of many polar craters,[97] are permanently shadowed, these "craters of eternal darkness" have extremely low temperatures. The Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F)[98] and just 26 K (−247 °C; −413 °F) close to the winter solstice in the north polar crater Hermite. This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of Pluto.[96]
Blanketed on top of the Moon's crust is a highly comminuted (broken into ever smaller particles) and impact gardened mostly gray surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder.[99] The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–15 m (33–49 ft) in the highlands and 4–5 m (13–16 ft) in the maria.[100] Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometers thick.[101]
These extreme conditions for example are considered to make it unlikely for spacecraft to harbor bacterial spores at the Moon longer than just one lunar orbit.[102]
Surface features
Main articles: Selenography, Lunar terrane, List of lunar features, and List of quadrangles on the Moon
Astronaut Harrison H. Schmitt next to a large Moon boulder
The topography of the Moon has been measured with laser altimetry and stereo image analysis.[103] Its most extensive topographic feature is the giant far-side South Pole–Aitken basin, some 2,240 km (1,390 mi) in diameter, the largest crater on the Moon and the second-largest confirmed impact crater in the Solar System.[104][105] At 13 km (8.1 mi) deep, its floor is the lowest point on the surface of the Moon.[104][106] The highest elevations of the Moon's surface are located directly to the northeast, which might have been thickened by the oblique formation impact of the South Pole–Aitken basin.[107] Other large impact basins such as Imbrium, Serenitatis, Crisium, Smythii, and Orientale possess regionally low elevations and elevated rims.[104] The far side of the lunar surface is on average about 1.9 km (1.2 mi) higher than that of the near side.[1]
The discovery of fault scarp cliffs suggest that the Moon has shrunk by about 90 metres (300 ft) within the past billion years.[108] Similar shrinkage features exist on Mercury. Mare Frigoris, a basin near the north pole long assumed to be geologically dead, has cracked and shifted. Since the Moon doesn't have tectonic plates, its tectonic activity is slow and cracks develop as it loses heat.[109]
Volcanic features
Main article: Volcanism on the Moon
The names of the main maria (blue) and some crater (brown) features of the near side of the Moon
The main features visible from Earth by the naked eye are dark and relatively featureless lunar plains called maria (singular mare; Latin for "seas", as they were once believed to be filled with water)[110] are vast solidified pools of ancient basaltic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water.[111] The majority of these lava deposits erupted or flowed into the depressions associated with impact basins. Several geologic provinces containing shield volcanoes and volcanic domes are found within the near side "maria".[112]
Almost all maria are on the near side of the Moon, and cover 31% of the surface of the near side[60] compared with 2% of the far side.[113] This is likely due to a concentration of heat-producing elements under the crust on the near side, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt.[65][114][115] Most of the Moon's mare basalts erupted during the Imbrian period, 3.3–3.7 billion years ago, though some being as young as 1.2 billion years[55] and as old as 4.2 billion years.[56]
In 2006, a study of Ina, a tiny depression in Lacus Felicitatis, found jagged, relatively dust-free features that, because of the lack of erosion by infalling debris, appeared to be only 2 million years old.[116] Moonquakes and releases of gas indicate continued lunar activity.[116] Evidence of recent lunar volcanism has been identified at 70 irregular mare patches, some less than 50 million years old. This raises the possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer because of the greater concentration of radioactive elements.[117][118][119][120] Evidence has been found for 2–10 million years old basaltic volcanism within the crater Lowell,[121][122] inside the Orientale basin. Some combination of an initially hotter mantle and local enrichment of heat-producing elements in the mantle could be responsible for prolonged activities on the far side in the Orientale basin.[123][124]
The lighter-colored regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent plagioclase cumulates of the lunar magma ocean.[56][55] In contrast to Earth, no major lunar mountains are believed to have formed as a result of tectonic events.[125]
The concentration of maria on the near side likely reflects the substantially thicker crust of the highlands of the Far Side, which may have formed in a slow-velocity impact of a second moon of Earth a few tens of millions of years after the Moon's formation.[126][127] Alternatively, it may be a consequence of asymmetrical tidal heating when the Moon was much closer to the Earth.[128]
Impact craters
Further information: List of craters on the Moon
A gray, many-ridged surface from high above. The largest feature is a circular ringed structure with high walled sides and a lower central peak: the entire surface out to the horizon is filled with similar structures that are smaller and overlapping.
A view of a three kilometer deep larger crater Daedalus on the Moon's far side
A major geologic process that has affected the Moon's surface is impact cratering,[129] with craters formed when asteroids and comets collide with the lunar surface. There are estimated to be roughly 300,000 craters wider than 1 km (0.6 mi) on the Moon's near side.[130] The lunar geologic timescale is based on the most prominent impact events, including Nectaris, Imbrium, and Orientale; structures characterized by multiple rings of uplifted material, between hundreds and thousands of kilometers in diameter and associated with a broad apron of ejecta deposits that form a regional stratigraphic horizon.[131] The lack of an atmosphere, weather, and recent geological processes mean that many of these craters are well-preserved. Although only a few multi-ring basins have been definitively dated, they are useful for assigning relative ages. Because impact craters accumulate at a nearly constant rate, counting the number of craters per unit area can be used to estimate the age of the surface.[131] The radiometric ages of impact-melted rocks collected during the Apollo missions cluster between 3.8 and 4.1 billion years old: this has been used to propose a Late Heavy Bombardment period of increased impacts.[132]
High-resolution images from the Lunar Reconnaissance Orbiter in the 2010s show a contemporary crater-production rate significantly higher than was previously estimated. A secondary cratering process caused by distal ejecta is thought to churn the top two centimeters of regolith on a timescale of 81,000 years.[133][134] This rate is 100 times faster than the rate computed from models based solely on direct micrometeorite impacts.[135]
Lunar swirls
Main article: Lunar swirls
Wide angle image of a lunar swirl, the 70 kilometer long Reiner Gamma
Lunar swirls are enigmatic features found across the Moon's surface. They are characterized by a high albedo, appear optically immature (i.e. the optical characteristics of a relatively young regolith), and often have a sinuous shape. Their shape is often accentuated by low albedo regions that wind between the bright swirls. They are located in places with enhanced surface magnetic fields and many are located at the antipodal point of major impacts. Well known swirls include the Reiner Gamma feature and Mare Ingenii. They are hypothesized to be areas that have been partially shielded from the solar wind, resulting in slower space weathering.[136]
Presence of water
Main article: Lunar water
In 2008, NASA's Moon Mineralogy Mapper equipment on India's Chandrayaan-1 discovered, for the first time, water-rich minerals (shown in blue around a small crater from which they were ejected).
Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. However, since the 1960s, scientists have hypothesized that water ice may be deposited by impacting comets or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from solar wind, leaving traces of water which could possibly persist in cold, permanently shadowed craters at either pole on the Moon.[137][138] Computer simulations suggest that up to 14,000 km2 (5,400 sq mi) of the surface may be in permanent shadow.[97] The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.[139]
In years since, signatures of water have been found to exist on the lunar surface.[140] In 1994, the bistatic radar experiment located on the Clementine spacecraft, indicated the existence of small, frozen pockets of water close to the surface. However, later radar observations by Arecibo, suggest these findings may rather be rocks ejected from young impact craters.[141] In 1998, the neutron spectrometer on the Lunar Prospector spacecraft showed that high concentrations of hydrogen are present in the first meter of depth in the regolith near the polar regions.[142] Volcanic lava beads, brought back to Earth aboard Apollo 15, showed small amounts of water in their interior.[143]
The 2008 Chandrayaan-1 spacecraft has since confirmed the existence of surface water ice, using the on-board Moon Mineralogy Mapper. The spectrometer observed absorption lines common to hydroxyl, in reflected sunlight, providing evidence of large quantities of water ice, on the lunar surface. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm.[144] Using the mapper's reflectance spectra, indirect lighting of areas in shadow confirmed water ice within 20° latitude of both poles in 2018.[145] In 2009, LCROSS sent a 2,300 kg (5,100 lb) impactor into a permanently shadowed polar crater, and detected at least 100 kg (220 lb) of water in a plume of ejected material.[146][147] Another examination of the LCROSS data showed the amount of detected water to be closer to 155 ± 12 kg (342 ± 26 lb).[148]
In May 2011, 615–1410 ppm water in melt inclusions in lunar sample 74220 was reported,[149] the famous high-titanium "orange glass soil" of volcanic origin collected during the Apollo 17 mission in 1972. The inclusions were formed during explosive eruptions on the Moon approximately 3.7 billion years ago. This concentration is comparable with that of magma in Earth's upper mantle. Although of considerable selenological interest, this insight does not mean that water is easily available since the sample originated many kilometers below the surface, and the inclusions are so difficult to access that it took 39 years to find them with a state-of-the-art ion microprobe instrument.
Analysis of the findings of the Moon Mineralogy Mapper (M3) revealed in August 2018 for the first time "definitive evidence" for water-ice on the lunar surface.[150][151] The data revealed the distinct reflective signatures of water-ice, as opposed to dust and other reflective substances.[152] The ice deposits were found on the North and South poles, although it is more abundant in the South, where water is trapped in permanently shadowed craters and crevices, allowing it to persist as ice on the surface since they are shielded from the sun.[150][152]
In October 2020, astronomers reported detecting molecular water on the sunlit surface of the Moon by several independent spacecraft, including the Stratospheric Observatory for Infrared Astronomy (SOFIA).[153][154][155][156]
Earth–Moon system
See also: Satellite system (astronomy), Claimed moons of Earth, and Double planet
Orbit
Main articles: Orbit of the Moon and Lunar theory
A view of the rotating Earth and the far side of the Moon as the Moon passes on its orbit in between the observing DSCOVR satellite and Earth
The Earth and the Moon form the Earth-Moon satellite system with a shared center of mass, or barycenter. This barycenter stays located at all times 1,700 km (1,100 mi) (about a quarter of Earth's radius) beneath the Earth's surface, making the Moon seemingly orbit the Earth.
The orbital eccentricity is 0.055, indicating a slightly elliptical orbit.[1] The Lunar distance, or the semi-major axis of the geocentric lunar orbit, is approximately 400,000 km, which is a quarter of a million miles or 1.28 light-seconds, and a unit of measure in astronomy. This is not to be confused with the instantaneous Earth–Moon distance, or distance to the Moon, the momentanous distance from the center of Earth to the center of the Moon.
The Moon makes a complete orbit around Earth with respect to the fixed stars, its sidereal period, about once every 27.3 days[h] However, because the Earth-Moon system moves at the same time in its orbit around the Sun, it takes slightly longer, 29.5 days,[i][60] to return at the same lunar phase, completing a full cycle, as seen from Earth. This synodic period or synodic month is commonly known as the lunar month and is equal to the length of the solar day on the Moon.[157]
Due to tidal locking, the Moon has a 1:1 spin–orbit resonance. This rotation–orbit ratio makes the Moon's orbital periods around Earth equal to its corresponding rotation periods. This is the reason for only one side of the Moon, its so-called near side, being visible from Earth. That said, while the movement of the Moon is in resonance, it still is not without nuances such as libration, resulting in slightly changing perspectives, making over time and location on Earth about 59% of the Moon's surface visible from Earth.[158]
Unlike most satellites of other planets, the Moon's orbital plane is closer to the ecliptic plane than to the planet's equatorial plane. The Moon's orbit is subtly perturbed by the Sun and Earth in many small, complex and interacting ways. For example, the plane of the Moon's orbit gradually rotates once every 18.61 years,[159] which affects other aspects of lunar motion. These follow-on effects are mathematically described by Cassini's laws.[160]
Minimum, mean and maximum distances of the Moon from Earth with its angular diameter as seen from Earth's surface, to scale
Tidal effects
Main articles: Tidal force, Tidal acceleration, Tide, and Theory of tides
Simplified diagram of the Moon's gravity tidal effect on the Earth
The gravitational attraction that Earth and the Moon (as well as the Sun) exert on each other manifests in a slightly greater attraction on the sides of closest to each other, resulting in tidal forces. Ocean tides are the most widely experienced result of this, but tidal forces considerably affect also other mechanics of Earth, as well as the Moon and their system.
The lunar solid crust experiences tides of around 10 cm (4 in) amplitude over 27 days, with three components: a fixed one due to Earth, because they are in synchronous rotation, a variable tide due to orbital eccentricity and inclination, and a small varying component from the Sun.[161] The Earth-induced variable component arises from changing distance and libration, a result of the Moon's orbital eccentricity and inclination (if the Moon's orbit were perfectly circular and un-inclined, there would only be solar tides).[161] According to recent research, scientists suggest that the Moon's influence on the Earth may contribute to maintaining Earth's magnetic field.[162]
The cumulative effects of stress built up by these tidal forces produces moonquakes. Moonquakes are much less common and weaker than are earthquakes, although moonquakes can last for up to an hour – significantly longer than terrestrial quakes – because of scattering of the seismic vibrations in the dry fragmented upper crust. The existence of moonquakes was an unexpected discovery from seismometers placed on the Moon by Apollo astronauts from 1969 through 1972.[163]
The most commonly known effect of tidal forces are elevated sea levels called ocean tides.[164] While the Moon exerts most of the tidal forces, the Sun also exerts tidal forces and therefore contributes to the tides as much as 40% of the Moon's tidal force; producing in interplay the spring and neap tides.[164]
The tides are two bulges in the Earth's oceans, one on the side facing the Moon and the other on the side opposite. As the Earth rotates on its axis, one of the ocean bulges (high tide) is held in place "under" the Moon, while another such tide is opposite. As a result, there are two high tides, and two low tides in about 24 hours.[164] 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.
If the Earth were a water world (one with no continents) it would produce a tide of only one meter, and that tide would be very predictable, but the ocean tides are greatly modified by other effects:
the frictional coupling of water to Earth's rotation through the ocean floors
the inertia of water's movement
ocean basins that grow shallower near land
the sloshing of water between different ocean basins[165]
As a result, the timing of the tides at most points on the Earth is a product of observations that are explained, incidentally, by theory.
Delays in the tidal peaks of both ocean and solid-body tides cause torque in opposition to the Earth's rotation. This "drains" angular momentum and rotational kinetic energy from Earth's rotation, slowing the Earth's rotation.[164][161] That angular momentum, lost from the Earth, is transferred to the Moon in a process known as tidal acceleration, which lifts the Moon into a higher orbit while lowering orbital speed around the Earth.
Thus the distance between Earth and Moon is increasing, and the Earth's rotation is slowing in reaction.[161] Measurements from laser reflectors left during the Apollo missions (lunar ranging experiments) have found that the Moon's distance increases by 38 mm (1.5 in) per year (roughly the rate at which human fingernails grow).[166][167][168] Atomic clocks show that Earth's day lengthens by about 17 microseconds every year,[169][170][171] slowly increasing the rate at which UTC is adjusted by leap seconds.
This tidal drag makes the rotation of the Earth and the orbital period of the Moon very slowly match. This matching first results in tidally locking the lighter body of the orbital system, as is already the case with the Moon. Theoretically, in 50 billion years,[172] the Earth's rotation will have slowed to the point of matching the Moon's orbital period, causing the Earth to always present the same side to the Moon. However, the Sun will become a red giant, engulfing the Earth-Moon system, long before then.[173][174]
Position and appearance
See also: Lunar observation
Over one lunar month more than half of the Moon's surface can be seen from Earth's surface.
Libration, the slight variation in the Moon's apparent size and viewing angle over a single lunar month as viewed from Earth's north
The Moon's highest altitude at culmination varies by its lunar phase, or more correctly its orbital position, and time of the year, or more correctly the position of the Earth's axis. The full moon is highest in the sky during winter and lowest during summer (for each hemisphere respectively), with its altitude changing towards dark moon to the opposite.
At the North and South Poles the Moon is 24 hours above the horizon for two weeks every tropical month (about 27.3 days), comparable to the polar day of the tropical year. Zooplankton in the Arctic use moonlight when the Sun is below the horizon for months on end.[175]
The apparent orientation of the Moon depends on its position in the sky and the hemisphere of the Earth from which it is being viewed. In the northern hemisphere it is seen upside down compared to the view in the southern hemisphere.[176] Sometimes the "horns" of a crescent moon appear to be pointing more upwards than sideways. This phenomenon is called a wet moon and occurs more frequently in the tropics.[177]
The distance between the Moon and Earth varies from around 356,400 km (221,500 mi) to 406,700 km (252,700 mi) at perigee (closest) and apogee (farthest), respectively, making the Moon's apparent size fluctuate. On average the Moon's angular diameter is about 0.52° (on average) in the sky, roughly the same apparent size as the Sun (see § Eclipses). Additionally when close to the horizon a purely psychological effect, known as the Moon illusion, makes the Moon appear larger.[178]
Despite the Moon's tidal locking, the effect of libration makes about 59% of the Moon's surface visible from Earth over the course of one month.[158][60]
Rotation
Comparison between the Moon on the left, rotating tidally locked (correct), and with the Moon on the right, without rotation (incorrect)
The tidally locked synchronous rotation of the Moon as it orbits the Earth results in it always keeping nearly the same face turned towards the planet. The side of the Moon that faces Earth is called the near side, and the opposite the far side. The far side is often inaccurately called the "dark side", but it is in fact illuminated as often as the near side: once every 29.5 Earth days. During dark moon to new moon, the near side is dark.[179]
The Moon originally rotate