Outer space
Outer space, commonly shortened to space, is the near-vacuum between celestial bodies.[1] It is where all of the planets, stars, galaxies and other objects are found. It is the expanse that exists beyond Earth and its atmosphere.
On Earth, space begins at the Kármán line (100 km above sea level).[2] This is where Earth's atmosphere is said to stop and outer space begins. This is not a natural boundary but is a convention used by scientists and diplomats.
However, the space near Earth is quite crowded by astronomical standards. A list of spaces goes like this:
- Geospace is the region of outer space near Earth: it includes the upper region of the atmosphere and the magnetosphere.[3] The Van Allen radiation belt lies within the geospace. The space inside the magnetosphere is protected from radiation from the Sun. It has a low level of electrically charged particles.
- Interplanetary space is the space around the Sun and planets of the Solar System. It has the solar wind, a continuous stream of charged particles from the Sun. This stream creates a very thin atmosphere (the Heliosphere) for billions of miles or kilometers into space.
Interplanetary space has the magnetic field generated by the Sun.[4] Planets such as Jupiter, Saturn, Mercury and the Earth also have Magnetospheres. These magnetic fields can trap particles from the solar wind and other sources, creating belts of magnetic particles such as the Van Allen radiation belt. Planets without magnetic fields, such as Mars, have their atmospheres gradually stripped off by the solar wind.[5] - Interstellar space is the physical space in a galaxy not occupied by stars or their planetary systems. It continues to the edges of the galaxy, where it fades into the intergalactic void. Most of the mass in this space is made up of single hydrogen atoms, fewer helium atoms and a few heavier atoms formed in stars. Supernovae blow some of their atoms huge distances.
A number of molecules and tiny 0.1 μm dust particles do exist in interstellar space.[6] About four new types of molecule are discovered each year. Large regions of higher density matter known as molecular clouds allow chemical reactions to occur. This includes organic polyatomic species. Much of this chemistry is driven by collisions. - Intergalactic space does have 'cosmic voids' between the large-scale structures of the universe.
Exploration
Exploring space by direct travel is difficult, and more or less impossible beyond the near planets. Space contains no air beyond the Earth. It takes three days of travelling to reach the Moon and, depending on speed, it would take a very long time to reach the closest star (Proxima Centauri). Manned spacecraft are designed to keep air inside them and to protect astronauts from extreme temperatures. It is widely thought that people will not be able to travel to nearby stars. A serious problem for humans is the great times taken for interstellar flights, and the danger of radiation to human life.
We gain most of our information about the items in space from different kinds of telescopes. Some of them are space telescopes, put in outer space for a better view. Space probes also explore planets, comets and other space objects that are not too distant.
Outer Space Media
The 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.
This 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.
Part 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.
The 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
Because of the hazards of a vacuum, astronauts must wear a pressurized space suit while off-Earth and outside their spacecraft.
SpaceShipOne completed the first human private spaceflight in 2004, reaching an altitude of 100.12 km (62.21 mi).
2008 launch of the SM-3 missile used to destroy American reconnaissance satellite USA-193
A computer-generated image mapping the prevalence of artificial satellites and space debris around Earth in geosynchronous and low Earth orbit
Aurora australis observed from the International Space Station
Earth and the Moon as seen from cislunar space
Related pages
References
- ↑ Daintith, John; Gould, William (2012) [2006]. Collins Dictionary of Astronomy (Fifth ed.). HarperCollins. p. 414. ISBN 9780007918485.
- ↑ "Where does space start?", All About Space, Imagine Publishing, no. 1, p. 84, 2012-06-28
- ↑ Schrijver, Carolus J. & Siscoe, George L. 2010. Heliophysics: evolving solar activity and the climates of Space and Earth. Cambridge University Press, p363. ISBN 0-521-11294-X
- ↑ Papagiannis, Michael D. 1972. Space physics and space astronomy. Taylor & Francis, 12–149. ISBN 0-677-04000-8
- ↑ Johnson R.E. 1994. Plasma-induced sputtering of an atmosphere. Space Science Reviews 69 (3–4): 215–253. [1]
- ↑ Rauchfuss, Horst 2008. Chemical evolution and the origin of life. transl. T.N. Mitchell. Springer, p101. ISBN 3-540-78822-0