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Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near perfect vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7255 kelvins (−270.4245 °C; −454.7641 °F) +/-0.002 K. The plasma between galaxies is thought to account for about half of the baryonic (ordinary) matter in the universe, having a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is dark energy, a type of vacuum energy that is poorly understood. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space.
Outer space does not begin at a definite altitude above the Earth's surface. The Kármán line, an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit.
Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights. This was followed by crewed rocket flights and, then, crewed Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961. Due to the high cost of getting into space, human spaceflight has been limited to low Earth orbit and the Moon. On the other hand, uncrewed spacecraft have reached all of the known planets in the Solar System.
Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental issues, the economic cost of putting objects, including humans, into space is very high. (Full article...)
Uranus is the seventh planet from the Sun; it is the third largest and fourth most massive planet in the Solar System. Uranus was the first planet discovered in modern times. Though it is visible to the naked eye like the five classical planets, it was never recognised as a planet by ancient observers due to its dimness. Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the solar system. Uranus' atmosphere, although similar to Jupiter and Saturn in being composed primarily of hydrogen and helium, contains a higher proportion of "ices" such as water, ammonia and methane, along with the usual traces of hydrocarbons. It has the coldest planetary atmosphere in the solar system, with a minimum temperature of 49 K, and has a complex layered cloud structure in which water is thought to make up the lowest clouds, while methane makes up the uppermost layer of clouds. In 1986, images from the Voyager 2 space probe showed Uranus as a virtually featureless planet in visible light without the cloud bands or storms associated with the other giants. The wind speeds on Uranus can reach 250 m/s (560 mph).
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For a full launch schedule, see 2022 in spaceflight § Upcoming launches.
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Image 1A piece of a thermal blanket that may have come from the descent stage of the Perseverance (from Space debris)
Image 2Cosmic dust of the Horsehead Nebula as revealed by the Hubble Space Telescope. (from Cosmic dust)
Image 32008 launch of the SM-3 missile used to destroy American reconnaissance satellite USA-193
Image 4Large scale matter distribution in a cubic section of the universe. The blue fiber structures represent the matter and the empty regions in between represent the cosmic voids of the intergalactic medium. (from Outer space)
Image 5Porous chondrite interplanetary dust particle. (from Cosmic dust)
Image 6Whirlpool Galaxy (Messier 51) (from Space exploration)
Image 7Comet 103P/Hartley (2010) (from Space exploration)
Image 8A MESSENGER image from 18,000 km showing a region about 500 km across (2008) (from Space exploration)
Image 9Perseverance's backshell sitting upright on the surface of Jezero Crater (from Space debris)
Image 10A picture of Saturn taken by Cassini (2004) (from Space exploration)
Image 11Buzz Aldrin and Apollo 11's lunar lander on the Moon's surface (from Space exploration)
Image 12Baker-Nunn cameras were widely used to study space debris. (from Space debris)
Image 13Apollo 16 LEM Orion, the Lunar Roving Vehicle and astronaut John Young (1972) (from Space exploration)
Image 14Surface of Mars by the Spirit rover (2004) (from Space exploration)
Image 15A proposed timeline of the origin of space, from physical cosmology (from Outline of space science)
Image 17Delta-v's in km/s for various orbital maneuvers (from Space exploration)
Image 18Artistic image of a rocket lifting from a Saturn moon (from Space exploration)
Image 19Mars, as seen by the Hubble Space Telescope (2003) (from Space exploration)
Image 20Astronaut Buzz Aldrin had a personal Communion service when he first arrived on the surface of the Moon. (from Space exploration)
Image 21Astronaut Piers Sellers during the third spacewalk of STS-121, a demonstration of orbiter heat shield repair techniques (from Outline of space science)
Image 22Herbig–Haro object HH 110 ejects gas through interstellar space. (from Interstellar medium)
Image 23This light-year-long knot of interstellar gas and dust resembles a caterpillar. (from Interstellar medium)
Image 24The diversity found in the different types and scales of astronomical objects make the field of study increasingly specialized. (from Outline of space science)
Image 25A laser-guided observation of the Milky Way Galaxy at the Paranal Observatory in Chile in 2010 (from Outline of space science)
Image 26Gabbard diagram of almost 300 pieces of debris from the disintegration of the five-month-old third stage of the Chinese Long March 4 booster on 11 March 2000 (from Space debris)
Image 27A micrometeoroid left this crater on the surface of Space Shuttle Challenger's front window on STS-7. (from Space debris)
Image 28Most orbital flight actually takes place in upper layers of the atmosphere, especially in the thermosphere (not to scale) (from Space exploration)
Image 29SpaceShipOne completed the first human private spaceflight in 2004, reaching an altitude of 100.12 km (62.21 mi).
Image 30Artist's impression of dust formation around a supernova explosion. (from Cosmic dust)
Image 31Saudi officials inspect a crashed PAM-D module in January 2001. (from Space debris)
Image 32Aurora australis observed from the Space Shuttle Discovery, on STS-39, May 1991 (orbital altitude: 260 km)
Image 33V-2 Rocket in the Peenemünde Museum (from Space exploration)
Image 34Space Shuttle Endeavour had a major impact on its radiator during STS-118. The entry hole is about 5.5 mm (0.22 in), and the exit hole is twice as large. (from Space debris)
Image 35Major elements of 200 stratospheric interplanetary dust particles. (from Cosmic dust)
Image 36First television image of Earth from space, taken by TIROS-1. (1960) (from Space exploration)
Image 37Crew quarters on Zvezda the base ISS crew module (from Space exploration)
Image 38Orbit of 2020 SO (from Space debris)
Image 39The distribution of ionized hydrogen (known by astronomers as H II from old spectroscopic terminology) in the parts of the Galactic interstellar medium visible from the Earth's northern hemisphere as observed with the Wisconsin Hα Mapper (Haffner et al. 2003) harv error: no target: CITEREFHaffnerReynoldsTufteMadsen2003 (help). (from Interstellar medium)
Image 40The original Magdeburg hemispheres (lower left) used to demonstrate Otto von Guericke's vacuum pump (right)
Image 41The Long Duration Exposure Facility (LDEF) is an important source of information on small-particle space debris. (from Space debris)
Image 42Smooth chondrite interplanetary dust particle. (from Cosmic dust)
Image 43Cosmic dust of the Andromeda Galaxy as revealed in infrared light by the Spitzer Space Telescope. (from Cosmic dust)
Image 44Spatial density of LEO space debris by altitude, according to 2011 a NASA report to the United Nations Office for Outer Space Affairs (from Space debris)
Image 45Asteroid 4 Vesta, imaged by the Dawn spacecraft (2011) (from Space exploration)
Image 46New Horizons image of Charon (2015) (from Space exploration)
Image 47The interface between the Earth's surface and outer space. The Kármán line at an altitude of 100 km (62 mi) is shown. The layers of the atmosphere are drawn to scale, whereas objects within them, such as the International Space Station, are not. (from Outer space)
Image 48The United States' planned Space Launch System concept art (from Space exploration)
Image 49Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft.
Image 50Apollo CSM in lunar orbit (from Space exploration)
Image 51Triton as imaged by Voyager 2 (1989) (from Space exploration)
Image 52Phobos (moon) (2008) (from Space exploration)
Image 53Debris impacts on Mir's solar panels degraded their performance. The damage is most noticeable on the panel on the right, which is facing the camera with a high degree of contrast. Extensive damage to the smaller panel below is due to impact with a Progress spacecraft. (from Space debris)
Image 54Space Shuttle Discovery's lower starboard wing and Thermal Protection System tiles, photographed on STS-114 during an R-Bar Pitch Manoeuvre where astronauts examine the TPS for any damage during ascent (from Space debris)
Image 55Voyager 1 is the first artificial object to reach the interstellar medium. (from Interstellar medium)
Image 56Uranus as imaged by Voyager 2 (1986) (from Space exploration)
Image 57Atmospheric attenuation in dB/km as a function of frequency over the EHF band. Peaks in absorption at specific frequencies are a problem, due to atmosphere constituents such as water vapor (H2O) and carbon dioxide (CO2). (from Interstellar medium)
Image 58Cislunar space seen from Mars (from Outer space)
Image 59Spent upper stage of a Delta II rocket, photographed by the XSS 10 satellite (from Space debris)
Image 60The Blue Marble Earth picture taken during Apollo 17 (1972) (from Space exploration)
Image 61Timeline of Solar System exploration. (from Space exploration)
Image 62Model of Vostok spacecraft (from Space exploration)
Image 63Map showing the Sun located near the edge of the Local Interstellar Cloud and Alpha Centauri about 4 light-years away in the neighboring G-Cloud complex (from Interstellar medium)
Image 64The sparse plasma (blue) and dust (white) in the tail of comet Hale–Bopp are being shaped by pressure from solar radiation and the solar wind, respectively
Image 65Objects in Earth orbit including fragmentation debris. November 2020 NASA:ODPO (from Space debris)
Image 66This is an artist's concept of the metric expansion of space, where a volume of the Universe is represented at each time interval by the circular sections. At left is depicted the rapid inflation from the initial state, followed thereafter by steadier expansion to the present day, shown at right. (from Outer space)
Image 67Mariner 10 image of Venus (1974) (from Space exploration)
Image 68A computer-generated image representing the locations, but not relative sizes, of space debris as could be seen from high Earth orbit. The two main debris fields are the ring of objects in geosynchronous Earth orbit (GEO) and the cloud of objects in low Earth orbit (LEO). (from Space debris)
Image 69Zodiacal light caused by cosmic dust. (from Cosmic dust)
Image 70Chandra, Hubble, and Spitzer image NGC 1952 (from Space exploration)
Image 71Three-dimensional structure in Pillars of Creation. (from Interstellar medium)
Image 72Satellite hit by a space debris, animation by ESA (from Space debris)
Image 73A picture of Neptune taken by Voyager 2 (1989) (from Space exploration)
Image 74Part of the Hubble Ultra-Deep Field image showing a typical section of space containing galaxies interspersed by deep vacuum. Given the finite speed of light, this view covers the past 13 billion years of the history of outer space.
Image 75A dusty trail from the early Solar System to carbonaceous dust today. (from Cosmic dust)
Image 76Ganymede (moon) (from Space exploration)
Image 77Bow shock formed by the magnetosphere of the young star LL Orionis (center) as it collides with the Orion Nebula flow
Image 78Reconstruction of solar activity over 11,400 years. Period of equally high activity over 8,000 years ago marked. (from Space climate)
Image 79New Horizons image of Pluto (2015) (from Space exploration)
Image 80Sputnik 1, the first artificial satellite orbited Earth at 939 to 215 km (583 to 134 mi) in 1957, and was soon followed by Sputnik 2. See First satellite by country (Replica Pictured) (from Space exploration)
Image 81Star cluster Pismis 24 and NGC 6357 (from Space exploration)
Image 82The Moon (2010) (from Space exploration)
Image 83A view beneath the clouds of Titan, as seen in false colour, created from a mosaic of images taken by Cassini (2013) (from Space exploration)
Image 84Vanguard 1 is expected to remain in orbit for 240 years. (from Space debris)
Image 85Known orbit planes of Fengyun-1C debris one month after the weather satellite's disintegration by the Chinese ASAT (from Space debris)
Image 86MESSENGER image of Mercury (2013) (from Space exploration)
Image 87A drifting thermal blanket photographed in 1998 during STS-88. (from Space debris)
Image 88Concept art for a NASA Vision mission (from Space exploration)
Image 89The Moon as seen in a digitally processed image from data collected during the 1992 Galileo spacecraft flyby (from Space exploration)
Image 90Self-portrait of Curiosity rover on Mars's surface (from Space exploration)
Image 91Spatial density of space debris by altitude according to ESA MASTER-2001, without debris from the Chinese ASAT and 2009 collision events (from Space debris)
Image 92The first image taken by a human of the whole Earth, probably photographed by William Anders of Apollo 8. South is up; South America is in the middle. (from Outer space)
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