Outer space

spaceinterstellar spaceintergalactic mediuminterplanetary spacedeep spacecislunarcislunar spaceintergalactic spaceextraterrestrialinterstellar
Outer space, or simply space, is the expanse that exists beyond the Earth and between celestial bodies.wikipedia
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Cosmic dust

interstellar dustdustspace dust
Outer space is not completely empty—it is a hard 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.
Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, or has fallen on Earth.

Star

starsstellarmassive star
Local concentrations of matter have condensed into stars and galaxies.
For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space.

Plasma (physics)

plasmaplasma physicsplasmas
Outer space is not completely empty—it is a hard 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. There is also gas, plasma and dust, small meteors, and several dozen types of organic molecules discovered to date by microwave spectroscopy.
Plasma is mostly associated with stars, extending to the rarefied intracluster medium and possibly the intergalactic regions.

Space exploration

space missionexplorationspace missions
This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space.
Space exploration is the use of astronomy and space technology to explore outer space.

Kármán line

edge of spaceKarman linethe United States definition
However, the Kármán line, an altitude of 100 km above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping.
The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space.

Yuri Gagarin

GagarinYury Gagarinfirst cosmonaut
This was followed by manned rocket flights and, then, manned Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961.
Yuri Alekseyevich Gagarin (9 March 1934 – 27 March 1968) was a Soviet Air Forces pilot and cosmonaut who became the first human to journey into outer space, achieving a major milestone in the Space Race; his capsule Vostok 1 completed one orbit of Earth on 12 April 1961.

Spaceflight

space travelspace flightspace transport
Due to the high cost of getting into space, manned spaceflight has been limited to low Earth orbit and the Moon.
Spaceflight (or space flight) is ballistic flight into or through outer space.

Rocket launch

launchlaunchedlifted off
This was followed by manned rocket flights and, then, manned Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961.
Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform or from an airplane.

Galaxy

galaxiesgalacticgalactic nuclei
Local concentrations of matter have condensed into stars and galaxies.
The space between galaxies is filled with a tenuous gas (the intergalactic medium) having an average density of less than one atom per cubic meter.

Outer Space Treaty

Space Preservation Treaty1967 Outer Space TreatySpace
The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967.
Among its principles, it bars states party to the treaty from placing weapons of mass destruction in Earth orbit, installing them on the Moon or any other celestial body, or otherwise stationing them in outer space.

Universe

physical worldThe Universeuniverses
Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space.
Such contents comprise all of energy in its various forms, including electromagnetic radiation and matter, and therefore planets, moons, stars, galaxies, and the contents of intergalactic space.

Otto von Guericke

Guerickevon GuerickeGuericke, Otto Von
In 1650, German scientist Otto von Guericke constructed the first vacuum pump: a device that would further refute the principle of horror vacui.
His major scientific achievements were the establishment of the physics of vacuums, the discovery of an experimental method for clearly demonstrating electrostatic repulsion, and his advocacy for the reality of "action at a distance" and of "absolute space".

Spaceflight osteopenia

(osteopenia)bone density lossbone deterioration
Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss.
Astronauts lose an average of more than 1% bone mass per month spent in space.

Hydrogen

HH 2 hydrogen gas
Outer space is not completely empty—it is a hard 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.
Most interstellar hydrogen is in the form of atomic hydrogen because the atoms can seldom collide and combine.

Vacuum

free spaceevacuatedhigh vacuum
Outer space is not completely empty—it is a hard 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.
Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space.

Solar System

outer Solar Systeminner Solar Systemouter planets
On the other hand, unmanned spacecraft have reached all of the known planets in the Solar System.
This releases an enormous amount of energy, mostly radiated into space as electromagnetic radiation peaking in visible light.

Earth

Earth's surfaceterrestrialworld
Outer space, or simply space, is the expanse that exists beyond the Earth and between celestial bodies.
The Kármán line, defined as 100 km above Earth's surface, is a working definition for the boundary between the atmosphere and outer space.

Radiation pressure

solar radiation pressurelight pressurepressure of light
Above this altitude, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar wind.
This particularly includes objects in outer space where it is usually the main force acting on objects besides gravity, and where the net effect of a tiny force may have a large cumulative effect over long periods of time.

Astronomical radio source

radio sourceradio sourcesradio
Non-thermal radio sources have been detected even among the most distant, high-z sources, indicating the presence of magnetic fields.
Astronomical radio sources are objects in outer space that emit strong radio waves.

Interstellar medium

interstellar gasinterstellar matterinterstellar
Interplanetary space extends to the heliopause, whereupon the solar wind gives way to the winds of the interstellar medium.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.

Heliosphere

heliopausetermination shockheliosheath
Interplanetary space is defined by the solar wind, a continuous stream of charged particles emanating from the Sun that creates a very tenuous atmosphere (the heliosphere) for billions of kilometers into space.
The heliosphere is the vast, bubble-like region of space which surrounds and is created by the Sun.

Meteoroid

meteormeteorsfireball
There is also gas, plasma and dust, small meteors, and several dozen types of organic molecules discovered to date by microwave spectroscopy.
A meteoroid is a small rocky or metallic body in outer space.

Radio galaxy

radio galaxiesradio lobeextragalactic radio sources
Magneto-hydrodynamic processes in active elliptical galaxies produce their characteristic jets and radio lobes.
Recently, much work has been done on the effects of these objects on the intergalactic medium, particularly in galaxy groups and clusters.

Thermosphere

as high as 180 –Earth's thermospherehigh altitudes
The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather.
In the exosphere, beginning at about 600 km (375 mi) above sea level, the atmosphere turns into space, although by the judicial criteria set for the definition of the Kármán line, the thermosphere itself is part of space.

Earth's magnetic field

geomagnetismgeomagneticgeomagnetic field
Geospace is populated by electrically charged particles at very low densities, the motions of which are controlled by the Earth's magnetic field.
It extends several tens of thousands of kilometers into space, protecting the Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects the Earth from harmful ultraviolet radiation.