Earth has often been personified as a deity, in particular a goddess. In many cultures the mother goddess, also called the Mother Earth, is also portrayed as a fertility deity.
To the Greeks, Gaia was the goddess personifying the Earth. The Chinese Earth goddess Hou-T'u is similar to Gaia, the deification of the Earth. In Norse mythology, the Earth goddess Jord was the mother of Thor and the daughter of Annar. Ancient Egyptian mythology is different from that of other cultures because Earth is male, Geb, and sky is female, Nut. To the Aztec, earth was called Tonantzin—"our mother".
In many religions, accounts of creation of the earth exist, recalling a story involving the creation of the Earth by a supernatural deity or deities.
Although commonly thought to be a sphere, the Earth is actually an oblate spheroid. It bulges slightly at the equator and is slightly flattened at the poles, amounting to a difference of about 0.3 %. In the ancient past there were varying levels of belief in a flat Earth, with the Mesopotamian culture portraying the world as a flat disk afloat in an ocean. The spherical form of the Earth was suggested by early Greek philosophers; a belief espoused by Pythagoras. By the Middle Ages—as evidenced by thinkers such as Thomas Aquinas—European belief in a spherical earth was widespread. Prior to the introduction of space flight, belief in a spherical Earth was based on observations of the secondary effects of the Earth's shape and parallels drawn with the shape of other planets.
Cartography, the study and practice of map making, and vicariously geography, have historically been the disciplines devoted to depicting the Earth. Surveying, the determination of locations and distances, to a lesser extent navigation, the determination of position and direction, have developed alongside cartography and geography, providing and suitably quantifying the requisite information.
The technological developments of the latter half of the 20th century are widely considered to have altered the public's perception of the Earth. Before space flight, the popular image of Earth was of a green world. Science fiction artist Frank R. Paul provided perhaps the first image of a cloudless blue planet (with sharply defined land masses) on the back cover of the July 1940 issue of Amazing Stories, a common depiction for several decades thereafter.
Apollo 17's 1972 "Blue Marble" photograph of Earth from cislunar space became the current iconic image of the planet as a marble of cloud-swirled blue ocean broken by green-brown continents. A photo taken of a distant Earth by Voyager 1 in 1990 inspired Carl Sagan to describe the planet as a "Pale Blue Dot." Earth has also been described as a massive spaceship, with a life support system that requires maintenance, or as having a biosphere that forms one large organism.
Over the past two centuries a growing environmental movement has emerged that is concerned about humankind's effects on the Earth. The key issues of this socio-political movement are the conservation of natural resources, elimination of pollution, and the usage of land. Environmentalists advocate sustainable management of resources and stewardship of the natural environment through changes in public policy and individual behavior. Of particular concern is the large-scale exploitation of non-renewable resources. Changes sought by the environmental movements are often in conflict with commercial interests due to the significant additional costs associated with managing the environmental impact
· 1 decade ago