History of Moon in Timeline

The Moon is Earth's only natural satellite, orbiting at an average distance of 384,399 km. Its orbital and rotational periods are synchronized by Earth's gravity at approximately 29.5 Earth days. This synchronization results in the same side of the Moon always facing Earth. The Moon's gravitational pull is the primary cause of Earth's tides.

1920: Comparative Studies for Lunar Stratigraphy

From 1920 to the 1940s, comparative studies supported the proposal that lunar craters were formed by collisions, leading to the development of lunar stratigraphy.

1957: Launch of Sputnik 1

In 1957, the launch of Sputnik 1 marked the beginning of the space age and the International Geophysical Year, paving the way for lunar exploration.

1958: Unsuccessful Luna Missions

In 1958, the Soviet Union experienced three unnamed failed missions in its Luna program.

1959: Luna 1 and Luna 2 Missions

In 1959, the Soviet Union's Luna 1 became the first human-made object to escape Earth's gravity and pass near the Moon. Later that year, Luna 2 became the first human-made object to reach the Moon's surface by intentionally impacting it.

1961: Kennedy's Moon Landing Commitment

In 1961, President John F. Kennedy committed the United States to a crewed Moon landing before the end of the decade, leading to NASA's lunar exploration programs.

1966: Luna 9 and Luna 10 Missions

In 1966, the Soviet Union's Luna 9 performed the first successful lunar soft landing, and Luna 10 became the first vehicle to orbit the Moon.

1968: Apollo 8 Orbits the Moon

In 1968, Apollo 8 made the first human mission to lunar orbit. Three months earlier, the Soviet Union's Zond 5 carried the first Earthlings (two tortoises) around the Moon.

July 20, 1969: First Human Landing on the Moon

On July 20, 1969, the United States' Apollo 11 mission achieved the first human landing on the Moon at Mare Tranquillitatis. The lander Eagle carried humans to the lunar surface for the first time.

July 21, 1969: First Person on the Moon

On July 21, 1969 (02:56 UTC), Neil Armstrong became the first person to set foot on the Moon as commander of the American Apollo 11 mission. The event was watched by an estimated 500 million people worldwide.

1969: Moonquakes Discovery

In 1969, seismometers placed on the Moon by Apollo astronauts made the unexpected discovery of moonquakes.

1972: Apollo 17 Mission

In 1972, Apollo 17 marked the last crewed mission to the Moon.

1972: Continued Moonquake Monitoring

Through 1972, Apollo astronauts continued to monitor moonquakes using seismometers placed on the Moon, finding them much less common and weaker than earthquakes, but longer lasting.

1973: Explorer 49 Mission

In 1973, Explorer 49 was the last dedicated U.S. probe to the Moon until the 1990s.

1977: End of Data Transmission

In late 1977, direct transmission of data from scientific instrument packages installed on the lunar surface during Apollo landings concluded due to budgetary considerations.

1994: Evidence of Water Pockets

In 1994, the bistatic radar experiment on the Clementine spacecraft indicated the existence of small, frozen pockets of water close to the lunar surface, although later observations questioned if these were rocks ejected from impact craters.

1998: Lunar Prospector Mission Begins

In 1998, the NASA Lunar Prospector mission began collecting data that later led to the discovery of hydrogen-rich areas, speculated to be former water ice.

1998: Detection of Hydrogen Concentrations

In 1998, the neutron spectrometer on the Lunar Prospector spacecraft detected high concentrations of hydrogen in the first meter of depth in the regolith near the lunar polar regions, suggesting the presence of water ice.

2006: Study of Ina Depression

In 2006, a study of Ina, a tiny depression in Lacus Felicitatis, revealed jagged, relatively dust-free features appearing to be only 2 million years old, suggesting recent lunar activity.

2007: Lunar Origin Models

In 2007, lunar formation models suggested a larger fraction of the Moon derived from the proto-Earth, contrary to previous simulations indicating the Moon mostly came from the impactor Theia. The models aim to explain the isotopic similarities between Earth and the Moon.

2008: Confirmation of Surface Water Ice

In 2008, the Chandrayaan-1 spacecraft confirmed the existence of surface water ice using the Moon Mineralogy Mapper, observing absorption lines common to hydroxyl in reflected sunlight.

2009: LCROSS Water Detection

In 2009, the LCROSS mission sent a 2,300 kg impactor into a permanently shadowed polar crater, detecting at least 100 kg of water in the plume of ejected material.

2010: Discovery of Lunar Cave Entrance

In 2010, photos taken by NASA's Lunar Reconnaissance Orbiter revealed a cave on the Moon near the Sea of Tranquillity, identified as an entry point to a collapsed lava tube. The cave measures roughly 45 meters wide and up to 80 meters long.

May 2011: Water Found in Lunar Sample

In May 2011, scientists reported 615–1410 ppm water in melt inclusions in lunar sample 74220, the high-titanium "orange glass soil" collected during the Apollo 17 mission.

2016: Discovery of Hydrogen-Rich Areas

In 2016, planetary scientists found two hydrogen-rich areas on opposite sides of the Moon using data collected on the 1998-99 NASA Lunar Prospector mission, speculating they were former poles before the Moon was tidally locked.

August 2018: Definitive Evidence of Water-Ice

In August 2018, analysis of the Moon Mineralogy Mapper (M3) revealed "definitive evidence" for water-ice on the lunar surface, identifying distinct reflective signatures in permanently shadowed craters.

2018: Indirect Lighting Confirmed Water Ice

In 2018, indirect lighting of shadowed areas within 20° latitude of both poles confirmed water ice using the Moon Mineralogy Mapper's reflectance spectra.

October 2020: Detection of Molecular Water

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).

2022: Simulations of Lunar Formation

A study published in 2022 using high-resolution simulations, found that giant impacts can immediately place a satellite with similar mass and iron content to the Moon into orbit far outside Earth's Roche limit. Satellites that initially pass within the Roche limit can reliably and predictably survive, by being partially stripped and then torqued onto wider, stable orbits.

November 1, 2023: Remnants of Theia Found Inside Earth

On November 1, 2023, scientists reported computer simulations indicating that remnants of Theia, the hypothetical celestial body that collided with Earth to form the Moon, might still be present inside the Earth.