| Outer Space is comprised of the relatively empty | | | | the outer space. The observable universe is filled with |
| regions of the universe out side the atmospheres of | | | | photons which are the cosmic background radiation |
| the celestial bodies (for instance, Earth, or the other | | | | which has an equally correspondingly number of |
| planets in our solar system). Outer space is used to | | | | neutrinos. |
| distinguish from airspace and terrestrial locations, it is | | | | The atmospheric density within outer space produces |
| not completely empty but contains low density | | | | drag on satellites. Most artificial satellites stay in low |
| particles as well as dark energy and dark matter. | | | | Earth orbit to deal with this drag, and fire their engines |
| Space is the closest form to a perfect vacuum that | | | | every few days to maintain orbit. Planets are too |
| has been found. It has no friction, which allows all of | | | | massive to be affected by the drag of the Solar |
| the celestial objects within it to move along at | | | | System. |
| whichever gravitational trajectory it is a part of. | | | | A human exposed to the vacuum of space would not |
| The Celestial objects keep their atmospheres by | | | | die from exposure, but would rather quickly asphyxiate |
| adhering to their gravitational attraction. Every | | | | due to the intense pressure and lack of air in outer |
| gravitational field has a different density. For instant, the | | | | space. Once the deoxygenated blood reached the |
| Earth's atmospheric gas simply decreases with | | | | brain, death would quickly follow. Cold or oxygen rich |
| distance from the object. The Earth's atmospheric | | | | atmospheres can survive at as long as the oxygen |
| pressure drops to about 1 Pa (10-3 Torr) at 100 km of | | | | density is similar to that of a standard-sea level |
| altitude, which is a common definition of boundary in | | | | atmosphere. |