Portal:Outer space

The Outer Space Portal

Introduction

Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft.

Outer space (or simply space) is the expanse that exists beyond Earth's atmosphere and between celestial bodies. It contains ultra-low levels of particle densities, constituting a near-perfect vacuum of predominantly hydrogen and helium plasma, permeated by electromagnetic radiation, cosmic rays, neutrinos, magnetic fields and dust. 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.

The concept that the space between the Earth and the Moon must be a vacuum was first proposed in the 17th century after scientists discovered that air pressure decreased with altitude. The immense scale of outer space was grasped in the 20th century when the distance to the Andromeda Galaxy was first measured. Humans began the physical exploration of space later in the same 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

Planetary habitability is the measure of an astronomical body's potential for developing and sustaining life. It may be applied both to planets and to the natural satellites of planets. The only absolute requirement for life is an energy source (usually but not necessarily solar energy), but the notion of planetary habitability implies that many other geophysical, geochemical, and astrophysical criteria must be met before an astronomical body is able to support life. The idea that planets beyond Earth might host life is an ancient one, though historically it was framed by philosophy as much as physical science. The late 20th century saw two breakthroughs in the field. To begin with, the observation and robotic exploration of other planets and moons within the solar system has provided critical information on defining habitability criteria and allowed for substantial geophysical comparisons between the Earth and other bodies. The discovery of extrasolar planets—beginning in 1995 and accelerating thereafter—was the second milestone. It confirmed that the Sun is not unique in hosting planets and expanded the habitability research horizon beyond our own solar system.

Selected picture

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  Pillars of Creation

  Photograph: NASA, ESA, and the Hubble Heritage Team

  The Pillars of Creation, a series of elephant trunks of interstellar gas and dust in the Eagle Nebula, are the subject of a famous Hubble Space Telescope photograph taken in 1995. They are so named because the depicted gas and dust, while being eroded by the light from nearby stars, are in the process of creating new stars. Shown here is a 2014 rephotograph, which was unveiled in 2015 as part of the telescope's 25th anniversary celebrations.
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  433 Eros asteroid

  433 Eros

  Credit: NASA

  The 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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  Eagle Nebula

  Photo credit: NASA

  The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611) is a young open cluster of stars. The nebula is an active region of star formation. Light from the bright, hot, young stars near the centre of the cluster illuminate the clouds of hydrogen gas and dust still collapsing to form new stars.
  
  As projected on the sky, the Eagle Nebula lies in the constellation of Serpens Cauda. In three dimensions, it is relatively close to the Solar System being some 7,000 light years away on the edge of the Sagittarius Arm, the next nearest spiral arm towards the centre of the Milky Way.
  
  In fact, when the picture is not coloured, is only red colored, the "Eagle" can be seen as a dark spot in the center of the nebula.
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  Planet Mars

  Mars (planet)

  Credit: NASA

  Mars, 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.
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  Orion Nebula

  Orion Nebula

  Credit: Hubble Space Telescope

  A composite photo of the Orion Nebula, the closest region of star formation to Earth. It is composed of 520 separate images and NASA calls it "one of the most detailed astronomical images ever produced". The nebula is located below Orion's Belt and is visible to the naked eye at night. It is one of the most scrutinized and photographed objects in the night sky, and is among the most intensely-studied celestial features.
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  STS-1

  Photo credit: NASA

  A 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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  Jupiter

  Diagram: Kelvin Song

  A 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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  Kepler's Supernova

  Supernova remnant

  Credit: NASA

  This 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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  Husband Hill

  Photo credit: Spirit rover

  A 360° panorama taken during the descent from the summit of Husband Hill, one of the Columbia Hills in Gusev crater, Mars. This stitched image is composed of 405 individual images taken with five different filters on the panoramic camera over the course of five Martian days.
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  NGC 4449

  Photograph: NASA, ESA, A. Aloisi (STScI/ESA), and The Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

  An 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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  NGC 4414

  Photograph: Hubble Heritage Team (AURA/STScI/NASA)

  NGC 4414 is an unbarred spiral galaxy about 62 million light-years away in the constellation Coma Berenices. It is a flocculent spiral galaxy, with short segments of spiral structure but without the dramatic well-defined spiral arms of a grand design spiral. NGC 4414 is a very isolated galaxy, with no signs of past interactions with other galaxies.
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  Color-composite image of the Pleiades from the Digitized Sky Survey

  Pleiades (star cluster)

  Credit: NASA, ESA, AURA/Caltech, Palomar Observatory

  The Pleiades (also known as M45 or the Seven Sisters) is an open cluster in the constellation of Taurus. It is among the nearest to the Earth of all open clusters, probably the best known and certainly the most striking to the naked eye.

  
  
  
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  Needle Galaxy

  Photograph: Ken Crawford

  NGC 4565 (also known as the Needle Galaxy) is an edge-on spiral galaxy about 30 to 50 million light-years away in the constellation Coma Berenices. NGC 4565 is a giant spiral galaxy more luminous than the Andromeda Galaxy, and has a population of roughly 240 globular clusters, more than the Milky Way.
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  Helix Nebula

  Photograph: NASA/JPL-Caltech/University of Arizona

  The 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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  Pioneer plaque

  Pioneer plaque

  Credit: Carl Sagan, Frank Drake, Linda Salzman Sagan

  The Pioneer plaque, which was included on both Pioneer 10 and Pioneer 11 unmanned spacecraft, the first man-made objects to leave the Solar System. Made from gold-anodised aluminium, the plaque shows the figures of a man and a woman along with several symbols that are designed to provide information about the origin of the spacecraft. However, the mean time for the spacecraft to come within 30 astronomical units of a star is longer than the current age of our galaxy.
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  Uranus

  Photo: NASA/JPL/Voyager 2 mission

  Uranus 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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  Solar flare

  Photo: Goddard Space Flight Center

  A solar flare, a sudden flash of brightness observed over the Sun's surface or the solar limb which is interpreted as a large energy release, recorded on August 31, 2012. Such flares are often, but not always, followed by a colossal coronal mass ejection; in this instance, the ejection traveled at over 900 miles (1,400 km) per second.
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  Earthrise, as seen by Apollo 8

  Apollo 8

  Credit: William Anders

  "Earthrise," the first occasion in which humans saw the Earth seemingly rising above the surface of the Moon, taken during the Apollo 8 mission on December 24, 1968. This view was seen by the crew at the beginning of its fourth orbit around the Moon, although the very first photograph taken was in black-and-white. Note that the Earth is in shadow here. A photo of a fully lit Earth would not be taken until the Apollo 17 mission.

  
  
  
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  James Webb Space Telescope

  Photo: NASA/MSFC/David Higginbotham/Emmett Given

  Six beryllium mirror segments of the James Webb Space Telescope (JWST) undergoing a series of cryogenic tests at NASA's Marshall Space Flight Center in Huntsville, Alabama. The JWST is a planned space telescope that is a joint collaboration of 20 countries. It will orbit the Sun approximately 1,500,000 km (930,000 mi) beyond the Earth, around the L₂ Lagrange point. It is expected to launch in December 2021.
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  Pale Blue Dot

  Photo credit: NASA/JPL

  Pale 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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  Order of magnitude

  Image credit: Dave Jarvis

  An illustration of relative astronomical orders of magnitude, starting with the terrestrial planets of the Solar System in image 1 (top left) and ending with the largest known star, VY Canis Majoris, at the bottom right. The biggest celestial body in each image is shown on the left of the next frame.
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  Geostationary orbit

  Animation credit: Cmglee

  This is an animation showing geocentric satellite orbits, to scale with the Earth, at 3,600 times actual speed. The second-outermost (shown in grey) is a geostationary orbit, 35,786 kilometres (22,236 miles) above Earth's equator and following the direction of Earth's rotation, with an orbital period matching the planet's rotation period (a geosynchronous orbit). An object in such an orbit will appear to occupy a fixed position in the sky. Some 300 kilometres (190 miles) farther away is the graveyard orbit (brown), used for satellites at the end of their operational lives. Nearer to the Earth are the orbits of navigational satellites, such as Galileo (turquoise), BeiDou (beige), GPS (blue) and GLONASS (red), in medium Earth orbits. Much closer to the planet, and within the inner Van Allen belt, are satellites in low Earth orbit, such as the Iridium satellite constellation (purple), the Hubble Space Telescope (green) and the International Space Station (magenta).

Space-related portals

General images

The following are images from various outer space-related articles on Wikipedia.

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  NASA computer-generated image of debris objects in Earth orbit, c. 2005 (from Space debris)
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  First television image of Earth from space, taken by TIROS-1 (1960) (from Space exploration)
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  V-2 Rocket in the Peenemünde Museum (from Space exploration)
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  A drifting thermal blanket photographed in 1998 during STS-88 (from Space debris)
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  Space debris identified as WT1190F, burning up in a fireball over Sri Lanka (from Space debris)
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  A 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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  This light-year-long knot of interstellar gas and dust resembles a caterpillar. (from Interstellar medium)
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  Astronaut 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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  Artist's impression of dust formation around a supernova explosion. (from Cosmic dust)
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  After reentry, Delta 2 second stage pieces were found in South Africa. (from Space debris)
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  Gabbard 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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  Astronomers used the James Webb Space Telescope to image the warm dust around a nearby young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of the Solar System in infrared light. (from Cosmic dust)
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  South is up in the first image of Earth taken by a person, probably by Bill Anders (during the 1968 Apollo 8 mission) (from Outer space)
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  Perseverance's backshell sitting upright on the surface of Jezero Crater (from Space debris)
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  Timeline of the expansion of the universe, where visible space is represented by the circular sections. At left, a dramatic expansion occurs in the inflationary epoch, and at the center, the expansion accelerates. Neither time nor size are to scale. (from Outer space)
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  A proposed timeline of the origin of space, from physical cosmology (from Outline of space science)
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  A wide field view of outer space as seen from Earth's surface at night. The interplanetary dust cloud is visible as the horizontal band of zodiacal light, including the false dawn (edges) and gegenschein (center), which is visually crossed by the Milky Way (from Outer space)
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  Concept art for a NASA Vision mission (from Space exploration)
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  Large-scale matter distribution in a cubic section of the universe. The blue fiber-like 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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  Debris density in low Earth orbit (from Space debris)
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  Self-portrait of Curiosity rover on Mars's surface (from Space exploration)
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  A dusty trail from the early Solar System to carbonaceous dust today. (from Cosmic dust)
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  Porous chondrite dust particle (from Cosmic dust)
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  Tupan Patera on Jupiter's moon Io (from Space exploration)
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  Buzz Aldrin taking a core sample of the Moon during the Apollo 11 mission (from Space exploration)
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  Near-Earth space showing the low-Earth (blue), medium Earth (green), and high Earth (red) orbits. The last extends beyond the radius of geosynchronous orbits (from Outer space)
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  Earth and the Moon as seen from cislunar space on the 2022 Artemis 1 mission (from Outer space)
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  The original Magdeburg hemispheres (left) used to demonstrate Otto von Guericke's vacuum pump (right)
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  Apollo Command Service Module in lunar orbit (from Space exploration)
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  Spent upper stage of a Delta II rocket, photographed by the XSS 10 satellite (from Space debris)
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  Map 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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  Apollo 16 LEM Orion, the Lunar Roving Vehicle and astronaut John Young (1972) (from Space exploration)
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  Debris 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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  Objects in Earth orbit including fragmentation debris, November 2020, NASA: ODPO (from Space debris)
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  Major elements of 200 stratospheric interplanetary dust particles. (from Cosmic dust)
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  Voyager 1 is the first artificial object to reach the interstellar medium. (from Interstellar medium)
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  Space 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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  A computer-generated map of objects orbiting Earth, as of 2005. About 95% are debris, not working artificial satellites (from Outer space)
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  Baker-Nunn cameras were widely used to study space debris. (from Space debris)
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  Infographic showing the space debris situation in different kinds of orbits around Earth (from Space debris)
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  Artistic image of a rocket lifting from a Saturn moon (from Space exploration)
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  Atmospheric 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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  Spatial 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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  The 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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  Comet 103P/Hartley (2010) (from Space exploration)
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  Illustration of a satellite breaking up into multiple pieces at higher altitudes (from Space debris)
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  Bow shock formed by the magnetosphere of the young star LL Orionis (center) as it collides with the Orion Nebula flow
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  Herbig–Haro object HH 110 ejects gas through interstellar space. (from Interstellar medium)
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  A micrometeoroid left this crater on the surface of Space Shuttle Challenger's front window on STS-7. (from Space debris)
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  Crew quarters on Zvezda, the base ISS crew module (from Space exploration)
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  The 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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  For the first time, the NASA / ESA / Canadian Space Agency / James Webb Space Telescope has observed the chemical signature of carbon-rich dust grains at redshift z ≈ 7, which is roughly equivalent to one billion years after the birth of the Universe, this observation suggests exciting avenues of investigation into both the production of cosmic dust and the earliest stellar populations in our Universe. (from Cosmic dust)
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  Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while outside their spacecraft.
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  The Long Duration Exposure Facility (LDEF) is an important source of information on small-particle space debris. (from Space debris)
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  Model of Vostok spacecraft (from Space exploration)
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  Surface of Mars by the Spirit rover (2004) (from Space exploration)
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  Cosmic dust of the Horsehead Nebula as revealed by the Hubble Space Telescope. (from Cosmic dust)
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  Conventional anti-satellite weapons such as the SM-3 missile remain legal under the law of armed conflict, even though they create hazardous space debris (from Outer space)
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  The 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). (from Interstellar medium)
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  Astronaut Buzz Aldrin had a personal Communion service when he first arrived on the surface of the Moon. (from Space exploration)
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  Zodiacal light caused by cosmic dust. (from Cosmic dust)
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  Cosmic dust of the Andromeda Galaxy as revealed in infrared light by the Spitzer Space Telescope. (from Cosmic dust)
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  Known 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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  Vanguard 1 is expected to remain in orbit for 240 years. (from Space debris)
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  Illustration of Earth's atmosphere gradual transition into outer space (from Outer space)
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  Asteroid 4 Vesta, imaged by the Dawn spacecraft (2011) (from Space exploration)
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  A MESSENGER image from 18,000 km showing a region about 500 km across (2008) (from Space exploration)
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  A computer-generated animation by the European Space Agency representing space debris in low earth orbit at the current rate of growth compared to mitigation measures being taken (from Space debris)
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  Concept for a space-based solar power system to beam energy down to Earth (from Outer space)
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  The International Space Station is an orbiting laboratory for space applications and habitability. Visible in the background is yellow-green airglow of Earth's ionosphere and the interstellar field of the Milky Way. (from Outer space)
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  Saudi officials inspect a crashed PAM-D module in January 2001. (from Space debris)
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  Interstellar medium and astrosphere meeting (from Interstellar medium)
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  Spatial 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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  Reconstruction 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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  Delta-v's in km/s for various orbital maneuvers (from Space exploration)
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  View of an orbital debris hole made in the panel of the Solar Max satellite (from Space debris)
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  Three-dimensional structure in Pillars of Creation. (from Interstellar medium)
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  Smooth chondrite interplanetary dust particle. (from Cosmic dust)
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  Growth 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)

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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