Outer space, also simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace (and terrestrial locations). There is no discrete boundary between the Earth's atmosphere and space, as the atmosphere gradually attenuates with increasing altitude. Outer space within the Solar System is called interplanetary space, which passes over into interstellar space at what is known as the heliopause.
Outer space is certainly spacious, but it is far from empty. Outer space is sparsely filled with several dozen types of organic molecules discovered to date by microwave spectroscopy, blackbody radiation left over from the big bang and the origin of the universe, and cosmic rays, which include ionized atomic nuclei and various subatomic particles. There is also some gas, plasma and dust, and small meteors. Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to spacecraft. Some of this debris re-enters the atmosphere periodically.
Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet Mars possessed bodies of liquid water on the surface. For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen. If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.
Conditions on the other terrestrial planets, Mercury and Venus, appear to be too harsh to support life as we know it. But it has been conjectured that Europa, the fourth-largest moon of Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.
Recently, the team of Stéphane Udry have discovered a new planet named Gliese 581 g, which is an extrasolar planet orbiting the red dwarf star Gliese 581. Gliese 581 g appears to lie in the habitable zone of space surrounding the star, and therefore could possibly host life as we know it.
Read more about this topic: Nature
Other articles related to "earth":
... the mass of a given astronomical body such as the Sun or the Earth—is known as the standard gravitational parameter and is denoted ... Also, for celestial bodies such as the Earth and the Sun, the value of the product GM is known more accurately than each factor independently ... For Earth, using M⊕ as the symbol for the mass of the Earth, we have Calculations in celestial mechanics can also be carried out using the unit of solar mass rather than the standard SI unit kilogram ...
2004 FH is a near-Earth asteroid that was discovered on March 15, 2004, by the NASA-funded LINEAR asteroid survey ... metres in diameter and passed just 43,000 km (27,000 mi) above the Earth's surface on March 18, 2004, at 2208 UTC making it the 11th closest approach to Earth recorded as of 21 November 2008 (2008 -11-21 ... comparison, geostationary satellites orbit Earth at 35,790 km ...
... Main article Earth in culture The standard astronomical symbol of the Earth consists of a cross circumscribed by a circle ... the Solar System, humankind did not begin to view the Earth as a moving object in orbit around the Sun until the 16th century ... Earth has often been personified as a deity, in particular a goddess ...
... AS1 (also written 2004 AS1), also known by the temporary name AL00667, is a near-Earth asteroid, first discovered on January 13, 2004, by the LINEAR project ... web by the Minor Planet Center (MPC) suggesting an imminent collision with Earth on or about January 15 with a likelihood of 14 ... passed at a distance of 12 Gm (or 32 times the distance from the Earth to the Moon), posing no threat ...
Famous quotes containing the word earth:
“The earth had a single light afar,
A flickering, human pathetic light,
That was maintained against the night,
It seemed to me, by the people there,
With a Godforsaken brute despair.”
—Robert Frost (18741963)
“Youll never succeed in idealizing hard work. Before you can dig mother earth youve got to take off your ideal jacket. The harder a man works, at brute labour, the thinner becomes his idealism, the darker his mind.”
—D.H. (David Herbert)