Alexei LeonovAlexei Arkhipovich Leonov (30 May 1934 – 11 October 2019) was a Soviet and Russian cosmonaut and aviator, Air Forcemajor general, writer, and artist. On 18 March 1965, he became the first person to conduct a spacewalk, exiting the capsule during the Voskhod 2 mission for 12 minutes and 9 seconds. He was also selected to be the first Soviet person to land on the Moon although the project was eventually cancelled.
Space suitA space suit (or spacesuit) is an environmental suit used for protection from the harsh environment ofouter space. It mainly protects from outer space’s vacuum, as space suits are a highly specialized pressure suit, but it also protects against temperature extremes, as well as radiation and micrometeoroids. Basic space suits are worn as a safety precaution inside spacecrafts in case of loss of cabin pressure.
AstronautAn astronaut (from the Ancient Greekἄστρον (astron), meaning 'star', and ναύτης (nautes), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member of a spacecraft. Although generally reserved for professional space travelers, the term is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, and space tourists.
Neil ArmstrongNeil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who, as the commander of the 1969 Apollo 11 mission, became the first person to walk on the Moon. He was also a naval aviator, test pilot and university professor. Armstrong was born and raised near Wapakoneta, Ohio. He entered Purdue University, studying aeronautical engineering, with the United States Navy paying his tuition under the Holloway Plan.
Outer spaceVoid between celestial bodiesFor other uses, see Outer space (other).Being essentially empty, outer space allows the earliest (redder) galaxies to be viewed without obstruction, as in the Webb's First Deep Field image.Outer space, or simply space, is the expanse that exists beyond Earth's atmosphere and between celestial bodies.
SpacecraftA spacecraft is a vehicle that is designed to fly and operate in outer space. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket).
Soviet UnionThe Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a transcontinental country that spanned much of Eurasia from its formation in 1922 until its dissolution in 1991. It was the world's third-most populous country, the largest by area, and bordered twelve other countries.
European Space AgencyEuropean organisation dedicated to space explorationThe European Space Agency (ESA; pronounced ) is a 23-member international organisation devoted to space exploration. It has its headquarters in Paris and a staff of around 3,000 people globally as of 2025. ESA was founded in 1975 in the context of European integration. Its 2026 annual budget was around €8.3 billion.
Voskhod 2Voskhod 2 (Russian: Восход-2, lit. 'Sunrise-2') was a Soviet crewed space mission in March 1965. The Vostok-based Voskhod 3KD spacecraft with two crew members on board, Pavel Belyayev and Alexei Leonov, was equipped with an inflatable airlock. It established another milestone in space exploration when Alexei Leonov became the first person to leave the spacecraft in a specialised spacesuit to conduct a 12-minute spacewalk.
MoonNatural satellite orbiting EarthSurface absorbed doserate13.2 μGy/h(during lunar daytime)Surface equivalent doserate57.0 μSv/h(during lunar daytime)Apparent magnitude−2.5 to −12.9−12.74 (mean full moon)Absolute magnitude (H)0.2Angular diameter29.3 to 34.1 arcminutesAtmosphereSurface pressure10 Pa (1 picobar) (day)10 Pa (1 femtobar) (night)Composition by volumeHeArNeNaKHThe Moon is the only natural satellite of Earth.
Atmosphere of EarthGas layer surrounding EarthEarth's atmosphere from space, showing a blue layer at the stratosphere, above the clouds of the troposphere. The Moon is visible as a crescent in the background.The atmosphere of Earth consists of a layer of mixed gas (commonly referred to as air) that is retained by gravity, surrounding the Earth's surface. It contains variable quantities of suspended aerosols and particulates that create weather features such as clouds and hazes.
PlanetA planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune.*As an Amazon Associate I earn from qualifying purchases.