Space is the boundless and three-dimensional extent in which objects are known to exist and where events take place with respect to certain positions and direction. The subject of space can be discussed in a number of contexts. In terms of metaphysics, space has not been considered to be real by a number of philosophers through the course of history. Space is also discussed under the concept of relativity. The field of astronomy involves a deep study and understanding of space, which refers to the regions beyond the Earth and its atmosphere.