Portal:Outer space
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Introduction


Outer space, commonly referred to simply as 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 2.7 kelvins (−270 °C; −455 °F).
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 kinetic temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space. Most of the remaining mass-energy in the observable universe is made up of an unknown form, dubbed dark matter and dark energy.
Outer space does not begin at a definite altitude above 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. Certain portions of the upper stratosphere and the mesosphere are sometimes referred to as "near space". 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. The economic cost of putting objects, including humans, into space is very high, limiting human spaceflight 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 has a negative effect on human physiology that causes both muscle atrophy and bone loss. (Full article...)
Selected article
Earth is the fifth-largest planet of the eight in the Solar System. It is also the largest, most massive, and densest of the Solar System's four terrestrial planets. Home to millions of species, including humans, Earth is the only place in the Universe where life is known to exist. The planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. The world is expected to continue supporting life for another 0.5 billion years. Earth's outer surface is divided into several rigid segments that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core. Earth interacts with other objects in outer space, including the Sun and the Moon. The mineral resources of Earth, as well as the products of the biosphere, contribute resources that are used to support a global human population. The human inhabitants are grouped into about 200 independent sovereign states and have developed many views of the planet.
Selected picture
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Image 1A TRACE image of sunspots on the surface, or photosphere, of the sun from September 2002, is taken in the far ultraviolet on a relatively quiet day for solar activity. However, the image still shows a large sunspot group visible as a bright area near the horizon. Although sunspots are relatively cool regions on the surface of the sun, the bright glowing gas flowing around the sunspots have a temperature of over one million °C (1.8 million °F). The high temperatures are thought to be related to the rapidly changing magnetic field loops that channel solar plasma.
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Image 2Image credit: NASAA radar image of the surface of Venus, centered at 180 degrees east longitude. This composite image was created from mapping by the Magellan probe, supplemented by data gathered by the Pioneer orbiter, with simulated hues based on color images recorded by Venera 13 and 14. No probe has been able to survive more than a few hours on Venus's surface, which is completely obscured by clouds, because the atmospheric pressure is some 90 times that of the Earth's, and its surface temperature is around 450 °C (842 °F).
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Image 3The asteroid 433 Eros was named after the Greek god of love Eros. This S-type asteroid is the second-largest near-Earth asteroid. This image shows the view looking from one end of the asteroid across the gouge on its underside and toward the opposite end.
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Astronaut Bruce McCandless using a Manned Maneuvering Unit Credit: NASAA Manned Maneuvering Unit (MMU) is a jet pack (propulsion backpack that snaps onto the back of the space suit) which has been used on untethered spacewalks from NASA's Space Shuttle, allowing an astronaut to move independently from the shuttle. The MMU was used on three Shuttle missions in 1984. It was first tested on February 7 during mission STS-41-B by astronauts Bruce McCandless II (seen here) and Robert L. Stewart.
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Image 5Photo credit: New Horizons probeAn animation of an eruption by the Tvashtar Paterae volcanic region on the innermost of Jupiter's Galilean moons, Io. The ejecta plume is 330 km (205 mi) high, though only its uppermost half is visible in this image, as its source lies over the moon's limb on its far side. This animation consists of a sequence of five images taken by NASA's New Horizons probe on March 1, 2007, over the course of eight minutes from 23:50 UTC.
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Image 6Photo credit: Spitzer Space TelescopeThis infrared image shows hundreds of thousands of stars crowded into the swirling core of our spiral Milky Way galaxy. In visible-light pictures, this region cannot be seen at all because cosmic dust lying between Earth and the galactic center blocks our view.
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Planet Mars Credit: NASAMars, the fourth planet from the Sun, is named after the Roman god of war because of its blood red color. Mars has two small, oddly-shaped moons, Phobos and Deimos, named after the sons of the Greek god Ares. At some point in the future Phobos will be broken up by gravitational forces. The atmosphere on Mars is 95% carbon dioxide. In 2003 methane was also discovered in the atmosphere. Since methane is an unstable gas, this indicates that there must be (or have been within the last few hundred years) a source of the gas on the planet. -
Image 8Photo: Yuri Beletsky, ESOA laser shoots towards the centre of the Milky Way from the Very Large Telescope facility in Chile, to provide a laser guide star, a reference point in the sky for the telescope's adaptive optics (AO) system. AO technology improves the performance of optical systems by reducing the effect of atmospheric distortion. AO was first envisioned by Horace W. Babcock in 1953, but did not come into common usage until advances in computer technology during the 1990s made the technique practical.
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Image 9
Kepler's Supernova Credit: NASAThis Supernova remnant of Kepler's Supernova (SN 1604) is made up of the materials left behind by the gigantic explosion of a star. There are two possible routes to this end: either a massive star may cease to generate fusion energy in its core, and collapse inward under the force of its own gravity, or a white dwarf star may accumulate material from a companion star until it reaches a critical mass and undergoes a similar collapse. In either case, the resulting supernova explosion expels much or all of the stellar material with great force.
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Image 10Photo: Adam EvansThe Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away. The image, created using a hydrogen-alpha filter, also shows Messier objects 32 and 110, as well as NGC 206 and the star Nu Andromedae. On December 15, 1612, German astronomer Simon Marius became the first person to describe the galaxy using a telescope.
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Image 11A timed exposure of the first Space Shuttle mission, STS-1. The shuttle Columbia stands on launch pad A at Kennedy Space Center, the night before launch. The objectives of the maiden flight were to check out the overall Shuttle system, accomplish a safe ascent into orbit and to return to Earth for a safe landing.
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Image 12Pale Blue Dot is the name given to this 1990 photo of Earth taken from Voyager 1 when its vantage point reached the edge of the Solar System, a distance of roughly 3.7 billion miles (6 billion kilometres). Earth can be seen as a blueish-white speck approximately halfway down the brown band to the right. The light band over Earth is an artifact of sunlight scattering in the camera's lens, resulting from the small angle between Earth and the Sun. Carl Sagan came up with the idea of turning the spacecraft around to take a composite image of the Solar System. Six years later, he reflected, "All of human history has happened on that tiny pixel, which is our only home."
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Image 13Photograph: NASA/JPL-Caltech/University of ArizonaThe Helix Nebula is a large planetary nebula located in the constellation Aquarius. Discovered by Karl Ludwig Harding, probably before 1824, it is one of the closest to Earth of all the bright planetary nebulae, about 215 parsecs (700 light-years) away. It is similar in appearance to the Cat's Eye Nebula and the Ring Nebula.
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Image 14The Sombrero Galaxy is a spiral galaxy in the Virgo constellation. It was discovered in the late 1700s. It is about 28 million light years away and is just faint enough to be invisible to the naked eye but easily visible with small telescopes. In our sky, it is about one-fifth the diameter of the full moon. M104 is moving away from Earth at about 1,000 kilometers per second.
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Image 15Photo credit: Harrison SchmittAstronaut Eugene Cernan makes a short test drive of the lunar rover (officially, Lunar Roving Vehicle or LRV) during the early part of the first Apollo 17 extravehicular activity. The LRV was only used in the last three Apollo missions, but it performed without any major problems and allowed the astronauts to cover far more ground than in previous missions. All three LRVs were abandoned on the Moon.
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Image 16Uranus is the seventh planet from the Sun and the fourth most massive in the Solar System. In this photograph from 1986 the planet appears almost featureless, but recent terrestrial observations have found seasonal changes to be occurring.
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Image 17"The Blue Marble" is a famous photograph of Earth. NASA officially credits the image to the entire Apollo 17 crew — Eugene Cernan, Ronald Evans and Jack Schmitt — all of whom took photographic images during the mission. Apollo 17 passed over Africa during daylight hours and Antarctica is also illuminated. The photograph was taken approximately five hours after the spacecraft's launch, while en route to the Moon. Apollo 17, notably, was the last manned lunar mission; no humans since have been at a range where taking a "whole-Earth" photograph such as "The Blue Marble" would be possible.
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Image 18NGC 6357 is a diffuse nebula in the constellation Scorpius. This composite image of the nebula contains X-ray data from the Chandra X-ray Observatory and the ROSAT telescope (purple), infrared data from the Spitzer Space Telescope (orange), and optical data from the SuperCosmos Sky Survey (blue). Radiation from hot, young stars is energizing the cooler gas in the clouds that surround them. Often known as the Lobster Nebula, the astronomical object has also been termed the Madokami Nebula by fans of the anime Madoka Magica due to its supposed resemblance to the main character. Scientists at the Midcourse Space Experiment prefer the name War and Peace Nebula, because the bright, western part resembles a dove, while the eastern part looks like a skull in infrared images.
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Image 19Photograph: NASA, ESA, A. Aloisi (STScI/ESA), and The Hubble Heritage (STScI/AURA)-ESA/Hubble CollaborationAn image of NGC 4449, highlighting its qualities as a starburst galaxy. NGC 4449, an irregular galaxy in the constellation Canes Venatici located about 12 million light years from Earth, has a rate of star formation twice that of the Milky Way's satellite galaxy, the Large Magellanic Cloud. Interactions with nearby galaxies are thought to have influenced this star formation.
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Image 20Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet and the densest giant planet. Neptune is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. Neptune orbits the Sun once every 164.8 years at an average distance of 30.1 au (4.5 billion km; 2.8 billion mi). It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident.
This picture of Neptune was taken by NASA's Voyager 2 spacecraft in 1989, at a range of 4.4 million miles (7.1 million kilometres) from the planet, approximately four days before closest approach. The photograph shows the Great Dark Spot, a storm about the size of Earth, in the centre, while the fast-moving bright feature nicknamed the "Scooter" and the Small Dark Spot can be seen on the western limb. These clouds were seen to persist for as long as the spacecraft's cameras could resolve them. -
Image 21Diagram: Kelvin SongA diagram of Jupiter showing a model of the planet's interior, with a rocky core overlaid by a deep layer of liquid metallic hydrogen and an outer layer predominantly of molecular hydrogen. Jupiter's true interior composition is uncertain. For instance, the core may have shrunk as convection currents of hot liquid metallic hydrogen mixed with the molten core and carried its contents to higher levels in the planetary interior. Furthermore, there is no clear physical boundary between the hydrogen layers—with increasing depth the gas increases smoothly in temperature and density, ultimately becoming liquid.
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Image 22Photo credit: Mars Reconnaissance OrbiterFalse-color Mars Reconnaissance Orbiter image of a side of the Chasma Boreale, a canyon in the polar ice cap of the Planum Boreum (north pole of Mars). Light browns are layers of surface dust, greys and blues are layers of water and carbon dioxide ice. Regular geometric cracking is indicative of higher concentrations of water ice.
The Planum Boreum's permanent ice cap has a maximum depth of 3 km (1.9 mi). It is roughly 1200 km (750 mi) in diameter, an area equivalent to about 1½ times the size of Texas. The Chasma Boreale is up to 100 km (62.5 mi) wide and features scarps up to 2 km (1.25 mi) high. For a comparison, the Grand Canyon is approximately 1.6 km (1 mi) deep in some places and 446 km (279 mi) long but only up to 24 km (15 mi) wide.
Space-related portals
General images
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Image 1Known orbit planes of Fengyun-1C debris one month after the weather satellite's disintegration by the Chinese ASAT (from Space debris)
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Image 2A piece of a thermal blanket that may have come from the descent stage of the Perseverance (from Space debris)
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Image 3Space 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)
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Image 4Artist's impression of dust formation around a supernova explosion. (from Cosmic dust)
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Image 5Tupan Patera on Io (from Space exploration)
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Image 6Part 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.
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Image 7The 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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Image 8Debris 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)
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Image 9The interplanetary dust cloud illuminated and visible as zodiacal light, with its parts the false dawn, gegenschein and the rest of its band, which is visually crossed by the Milky Way (from Outer space)
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Image 10The original Magdeburg hemispheres (lower left) used to demonstrate Otto von Guericke's vacuum pump (right)
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Image 11The interface between 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)
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Image 12A laser-guided observation of the Milky Way Galaxy at the Paranal Observatory in Chile in 2010 (from Outline of space science)
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Image 13Saudi officials inspect a crashed PAM-D module in January 2001. (from Space debris)
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Image 14Spent upper stage of a Delta II rocket, photographed by the XSS 10 satellite (from Space debris)
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Image 15Spatial density of space debris by altitude according to ESA MASTER-2001, without debris from the Chinese ASAT and 2009 collision events (from Space debris)
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Image 16Apollo 16 LEM Orion, the Lunar Roving Vehicle and astronaut John Young (1972) (from Space exploration)
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Image 17Delta-v's in km/s for various orbital maneuvers (from Space exploration)
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Image 18The diversity found in the different types and scales of astronomical objects make the field of study increasingly specialized. (from Outline of space science)
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Image 192008 launch of the SM-3 missile used to destroy American reconnaissance satellite USA-193
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Image 20Baker-Nunn cameras were widely used to study space debris. (from Space debris)
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Image 21Artistic image of a rocket lifting from a Saturn moon (from Space exploration)
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Image 22This light-year-long knot of interstellar gas and dust resembles a caterpillar. (from Interstellar medium)
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Image 23Concept art for a NASA Vision mission (from Space exploration)
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Image 24Apollo CSM in lunar orbit (from Space exploration)
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Image 25Vanguard 1 is expected to remain in orbit for 240 years. (from Space debris)
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Image 26This is an artist's concept of the expansion of the universe, 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)
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Image 27Perseverance's backshell sitting upright on the surface of Jezero Crater (from Space debris)
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Image 28Model of Vostok spacecraft (from Space exploration)
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Image 29A computer-generated image mapping the prevalence of artificial satellites and space debris around Earth in geosynchronous and low Earth orbit (from Outer space)
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Image 30Three-dimensional structure in Pillars of Creation. (from Interstellar medium)
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Image 31A proposed timeline of the origin of space, from physical cosmology (from Outline of space science)
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Image 32Space 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)
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Image 33Atmospheric 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)
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Image 34Astronaut Buzz Aldrin had a personal Communion service when he first arrived on the surface of the Moon. (from Space exploration)
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Image 35A drifting thermal blanket photographed in 1998 during STS-88. (from Space debris)
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Image 36Spatial 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)
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Image 37A MESSENGER image from 18,000 km showing a region about 500 km across (2008) (from Space exploration)
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Image 38The Long Duration Exposure Facility (LDEF) is an important source of information on small-particle space debris. (from Space debris)
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Image 39Map 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)
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Image 40The 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.
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Image 41Cosmic dust of the Andromeda Galaxy as revealed in infrared light by the Spitzer Space Telescope. (from Cosmic dust)
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Image 42Astronaut Piers Sellers during the third spacewalk of STS-121, a demonstration of orbiter heat shield repair techniques (from Outline of space science)
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Image 43Satellite hit by a space debris; animation by ESA (from Space debris)
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Image 44Major elements of 200 stratospheric interplanetary dust particles. (from Cosmic dust)
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Image 45A computer-generated image representing the locations, but not relative sizes, of space debris as could be seen from high Earth orbit (HEO). 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)
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Image 46Voyager 1 is the first artificial object to reach the interstellar medium. (from Interstellar medium)
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Image 47Self-portrait of Curiosity rover on Mars's surface (from Space exploration)
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Image 48Zodiacal light caused by cosmic dust. (from Cosmic dust)
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Image 49Cosmic dust of the Horsehead Nebula as revealed by the Hubble Space Telescope. (from Cosmic dust)
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Image 50Outer space from the International Space Station at 400 km (250 mi) altitude in low Earth orbit. In the background the Milky Way's interstellar space is visible, as well as in the foreground, above Earth, the airglow of the ionosphere just below and beyond the so-defined edge of space the Kármán line in the thermosphere. (from Outer space)
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Image 51Large-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)
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Image 52Reconstruction of solar activity over 11,400 years. Period of equally high activity over 8,000 years ago marked. (from Space climate)
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Image 53The 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)
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Image 54Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft.
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Image 55A micrometeoroid left this crater on the surface of Space Shuttle Challenger's front window on STS-7. (from Space debris)
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Image 56Bow shock formed by the magnetosphere of the young star LL Orionis (center) as it collides with the Orion Nebula flow
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Image 57Orbit of 2020 SO (from Space debris)
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Image 58First television image of Earth from space, taken by TIROS-1. (1960) (from Space exploration)
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Image 59Objects in Earth orbit including fragmentation debris. November 2020 NASA:ODPO (from Space debris)
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Image 60Earth and the Moon as seen from cislunar space (from Outer space)
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Image 61Aurora australis observed from the International Space Station (from Outer space)
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Image 62Porous chondrite dust particle (from Cosmic dust)
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Image 63Asteroid 4 Vesta, imaged by the Dawn spacecraft (2011) (from Space exploration)
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Image 64Gabbard 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)
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Image 65Comet 103P/Hartley (2010) (from Space exploration)
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Image 66A dusty trail from the early Solar System to carbonaceous dust today. (from Cosmic dust)
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Image 67Growth of tracked objects in orbit and related events; efforts to manage outer space global commons have so far not reduced the debris or the growth of objects in orbit (from Space debris)
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Image 68SpaceShipOne completed the first human private spaceflight in 2004, reaching an altitude of 100.12 km (62.21 mi).
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Image 69Surface of Mars by the Spirit rover (2004) (from Space exploration)
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Image 70Smooth chondrite interplanetary dust particle. (from Cosmic dust)
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Image 71Herbig–Haro object HH 110 ejects gas through interstellar space. (from Interstellar medium)
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Image 72Crew quarters on Zvezda the base ISS crew module (from Space exploration)
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Image 73Buzz Aldrin taking a core sample of the Moon during the Apollo 11 mission (from Space exploration)
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Image 74V-2 Rocket in the Peenemünde Museum (from Space exploration)
Did you know (auto-generated)

- ... that, for the Space 220 Restaurant, Disney reached out to NASA engineers to understand what a space elevator might look like?
- ... that some severe environmental impacts of the invasion of Ukraine can be seen from space?
- ... that the space industry of India has supported the launch of more than 100 domestic satellites and more than 300 foreign satellites?
- ... that Nature's Fynd, producer of microbe-based meat substitutes, is working with NASA to develop a bioreactor for use in space travel?
- ... that Louis W. Roberts was among the highest ranking African-American space program staff at NASA while the Apollo program was underway?
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