From Wikipedia, the free encyclopedia

The geographical western hemisphere of Earth, highlighted in yellow.

Western Hemisphere

Western Hemisphere or Western hemisphere, is a geopolitical term for the Americas and associated islands and waters (or the New World). It is derived from the geographical term of western hemisphere, which is the half of the Earth that lies west of the Prime Meridian, the other half being the Eastern Hemisphere. Usage of the term Western Hemisphere has shifted in modernity so that the term generally refers collectively to the Americas and their inhabitants, including associated islands like the West Indies and Greenland, while excluding other territories that lie geographically in the hemisphere like parts of Africa, Europe, Antarctica, and Asia.

In other languages and sometimes in English, the term western hemisphere (not capitalised) is used in the literal sense, on par with the other geographical hemispheres. A hemisphere is a geometric term that literally means "half ball", and in geography the term is used when dividing the Earth into two halves. The most obvious dividing line is the equator, creating the northern and southern hemispheres. These hemispheres are based on unambiguous reference points — the north and south poles — which are defined by the Earth's axis of rotation and, in turn, define the equator. Any definition of eastern and western hemispheres, however, requires the selection of an arbitrary meridian and a corresponding meridian on the other side of the Earth. The Prime Meridian at 0° longitude is typically used, which runs through Greenwich (London) in the United Kingdom; this is used to define the International Date Line (or End Meridian) on the other side of the Earth at 180° longitude. Arguably, this is a Eurocentric choice, which would make the more common geopolitical meaning of 'the Americas' Eurocentric as well. In this context, the western hemisphere also includes the western portions of Europe and Africa, easternmost tip of Russia, numerous territories in Oceania, and a portion of Antarctica while excluding some of the Aleutian Islands to the southwest of the Alaskan mainland.

• Prime Meridian
• End Meridian
• International Date Line
• Americas
• Americas (terminology)