United States

Coordinates: 40°N 100°W / 40°N 100°W / 40; -100

The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major territories and various possessions. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America and the state of Hawaii is an archipelago in the mid-Pacific. The territories are scattered about the Pacific Ocean and the Caribbean Sea. At 3.8 million square miles (9.842 million km²) and with over 320 million people, the country is the world's third or fourth-largest by total area and the third most populous. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.

List of states and territories of the United States

The United States of America is a federal republic consisting of 50 states, a federal district (where the nation's seat of government–Washington, D.C.–is located), five major territories, and various possessions. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America (also bordering Canada) and the state of Hawaii is an archipelago in the mid-Pacific. The territories are scattered about the Pacific Ocean and the Caribbean Sea.

States are the primary subdivisions of the United States, and possess a number of powers and rights under the United States Constitution, such as regulating intrastate commerce, running elections, creating local governments, and ratifying constitutional amendments. Each state has its own constitution, grounded in republican principles, and government, consisting of three branches: executive, legislative, and judicial. All states and their residents are represented in the federal Congress, a bicameral legislature consisting of the Senate and the House of Representatives. Each state is represented by two Senators, while Representatives are distributed among the states in proportion to the most recent constitutionally mandated decennial census. Additionally, each state is entitled to select a number of electors to vote in the Electoral College, the body that elects the President of the United States, equal to the total of Representatives and Senators in Congress from that state.Article IV, Section 3, Clause 1 of the Constitution grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has expanded from the original 13 to 50. Each new state has been admitted on an equal footing with the existing states.

United States (disambiguation)

United States usually refers to the United States of America, a country in North America.

United States may also refer to:

Countries

Historical

Solar energy

Solar energy is radiant light and heat from the Sun harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture and artificial photosynthesis.

It is an important source of renewable energy and its technologies are broadly characterized as either passive solar or active solar depending on the way they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of electricity. The United Nations Development Programme in its 2000 World Energy Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ). This is several times larger than the total world energy consumption, which was 559.8 EJ in 2012.

Solar Energy (journal)

Solar Energy is a peer-reviewed scientific journal covering research on solar energy such as photovoltaics and solar heating, but also its indirect usages like wind power or bioenergy. It is published by Elsevier on behalf of the International Solar Energy Society. The editor-in-chief is Yogi Goswami. According to the Journal Citation Reports, the journal has a 2013 impact factor of 3.541.

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