Far side of the Moon in the context of "Apollo 8"

The physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made a deliberate impact on the surface of the Moon on 14 September, 1959. Prior to that the only available means of lunar exploration had been observations from Earth. The invention of the optical telescope brought about the first leap in the quality of lunar observations. Galileo Galilei is generally credited as the first person to use a telescope for astronomical purposes, having made his own telescope in 1609. The mountains and craters on the lunar surface were among his first observations.

Human exploration of the Moon since Luna 2 has consisted of both crewed and uncrewed missions. NASA's Apollo program has been the only program to successfully land humans on the Moon, which it did six times on the near side in the late 20th century. The first human landing took place in 1969, when the Apollo 11 astronauts Buzz Aldrin and Neil Armstrong touched down on the surface in the region of Mare Tranquillitatis, leaving scientific instruments upon the mission's completion and returning lunar samples to Earth. All lunar missions had taken place on the lunar near side until the first soft landing on the far side of the Moon was made by the CNSA robotic spacecraft Chang'e 4 in early 2019, which successfully deployed the Yutu-2 robotic lunar rover. On 25 June 2024, CNSA's Chang'e 6 conducted the first lunar sample return from the far side of the Moon.

The near side of the Moon is the hemisphere of the Moon that is facing Earth. While Earth keeps turning through its near side to the Moon, changing in the course of a day the part it faces toward the Moon, the Moon keeps the same surface (or "face") oriented to Earth. This is due to the Moon rotating on its axis at the same rate that the Moon orbits the Earth—a phenomenon known as tidal locking. The opposite hemisphere is the far side.

The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions from Earth cause the lunar phases. The near side when dark is faintly visible due to earthshine, which is indirect sunlight reflected from the surface of Earth and onto the Moon.

The lunar maria (/ˈmæri.ə/ MARR-ee-ə; sg. mare /ˈmɑːreɪ, -i/ MAR-ay, MAR-ee) are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to the naked eye. The maria cover about 16% of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters.

The term "mare" (sea) was used in astronomy in the beginnings of the 17th century, initially with the idea that the lunar spots were covered with water. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus ('lake'), palus ('marsh'), and sinus ('bay'). The last three are smaller than maria, but have the same nature and characteristics.

The origin of the Moon is usually explained by a Mars-sized body, known as Theia, striking the Earth, creating a debris ring that eventually collected into a single natural satellite, the Moon, but there are a number of variations on this giant-impact hypothesis, as well as alternative explanations, and research continues into how the Moon came to be formed. Other proposed scenarios include captured body, fission, formed together (accretion, synestia), planetesimal collisions (formed from asteroid-like bodies), and collision theories.

The standard giant-impact hypothesis suggests that a Mars-sized body called Theia impacted the proto-Earth, creating a large debris ring around Earth, which then accreted to form the Moon. This collision also resulted in the 23.5° tilted axis of the Earth, thus causing the seasons. The Moon's oxygen isotopic ratios seem to be essentially identical to Earth's. Oxygen isotopic ratios, which may be measured very precisely, yield a unique and distinct signature for each Solar System body. If Theia had been a separate protoplanet, it probably would have had a different oxygen isotopic signature than proto-Earth, as would the ejected mixed material. Also, the Moon's titanium isotope ratio (Ti/Ti) appears so close to the Earth's (within 4 parts per million) that little if any of the colliding body's mass could have been part of the Moon.

A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.

In 1969, Apollo 11 was the first crewed mission to land on the Moon. There were six crewed landings between 1969 and 1972 and numerous uncrewed landings. All crewed missions to the Moon were conducted by the Apollo program, with the last departing the lunar surface in December 1972. After Luna 24 in 1976, there were no soft landings— landings without significant damage—on the Moon until Chang'e 3 in 2013. All soft landings took place on the near side of the Moon until January 2019, when Chang'e 4 made the first landing on the far side of the Moon.

Selenography is the study of the surface and physical features of the Moon (also known as geography of the Moon, or selenodesy). Like geography and areography, selenography is a subdiscipline within the field of planetary science. Historically, the principal concern of selenographists was the mapping and naming of the lunar terrane identifying maria, craters, mountain ranges, and other various features. This task was largely finished when high resolution images of the near and far sides of the Moon were obtained by orbiting spacecraft during the early space era. Nevertheless, some regions of the Moon remain poorly imaged (especially near the poles) and the exact locations of many features (like crater depths) are uncertain by several kilometers. Today, selenography is considered to be a subdiscipline of selenology, which itself is most often referred to as simply "Lunar science."

Missions to the Moon have been numerous and represent some of the earliest endeavours in space missions, with continuous exploration of the Moon beginning in 1959.

The first partially successful lunar mission was Luna 1 in January 1959, which became the first probe to escape Earth's gravity and perform a flyby of another astronomical body, passing near the Moon. Soon after, the first Moon landing—and the first landing on any extraterrestrial body—was carried out by Luna 2, which intentionally impacted the Moon on 14 September 1959. The far side of the Moon, permanently hidden from Earth due to tidal locking, was imaged for the first time by Luna 3 on 7 October 1959, revealing terrain never before seen.

The China National Space Administration (CNSA) is the national space agency of China. Headquartered in Haidian, Beijing, it is responsible for China's civil space programs and international space cooperation. The CNSA is a national bureau under the Ministry of Industry and Information Technology.

Founded in 1993, the CNSA has pioneered a number of achievements in space for China despite its relatively short history, including becoming the first space agency to land on the far side of the Moon with Chang'e 4, bringing material back from the Moon with Chang'e 5 and 6, and being the second agency who successfully landed a rover on Mars with Tianwen-1. Tianwen-2 is en route to explore the co-orbital near-Earth asteroid 469219 Kamoʻoalewa and the active asteroid 311P/PanSTARRS and collecting samples of the regolith of Kamo'oalewa.

Chang'e 4 (/tʃɑːŋˈə/; Chinese: 嫦娥四号; pinyin: Cháng'é Sìhào; lit. 'Chang'e No. 4') is a robotic spacecraft mission in the Chinese Lunar Exploration Program of the CNSA. It made a soft landing on the far side of the Moon, the first spacecraft to do so, on 3 January 2019.

A communication relay satellite, Queqiao, was first launched to a halo orbit near the Earth–Moon L₂ point in May 2018. The robotic lander and Yutu-2 (Chinese: 玉兔二号; pinyin: Yùtù Èrhào; lit. 'Jade Rabbit No. 2') rover were launched on 7 December 2018 and entered lunar orbit on 12 December 2018, before landing on the Moon's far side. On 15 January it was announced that seeds had sprouted in the lunar lander's biological experiment, the first plants to sprout on the Moon. The mission is the follow-up to Chang'e 3, the first Chinese landing on the Moon.