Earth (Zemlya)

Earth (Zemlya)
Name	Earth (Zemlya)
Type	Planet
Radius	6,371 km
Orbital period	365.256 days
Mass	5.972×10^24 kg
Satellites	Moon

Earth (Zemlya) is the third planet from the Sun and the only known astronomical object to harbor life. It has a diverse lithosphere, hydrosphere, and atmosphere that support complex biospheres and human civilizations. Earth participates in Solar System dynamics with planets like Mercury, Venus, Mars, and outer bodies such as Jupiter and Saturn.

Etymology and Names

The modern English name derives from Old English and Germanic roots comparable to Heimat and Erde; alternative names include Terra in Latin and Gaia in Greek tradition. Slavic languages use variants like Zemlya corresponding to terms found in Rus'. Scientific nomenclature references bodies such as Mercury (planet), Venus (planet), and Mars (planet) in planetary catalogs maintained by organizations like NASA, ESA, and Roscosmos.

Geology and Structure

Earth's internal structure comprises the inner core, outer core, mantle, and crust, concepts developed through seismology stemming from observations tied to events such as the 1906 San Francisco earthquake and research by figures associated with Wadati–Benioff zones and Andrija Mohorovičić. Plate tectonics explains continental drift related to features like the Mid-Atlantic Ridge, Himalaya formation due to the collision of the Indian Plate and Eurasian Plate, and rifting at the Great Rift Valley. Volcanism occurs at subduction zones exemplified by the Ring of Fire and at hotspots such as Hawaii (island) from mantle plumes. Geological time scales reference periods named after type localities like the Devonian and Cretaceous, with mass extinctions exemplified by the Cretaceous–Paleogene extinction event and the Permian–Triassic extinction event. Mineralogy and petrology link to discoveries at sites like Mount St. Helens and studies by institutions such as the United States Geological Survey and the Geological Society of London.

Atmosphere and Climate

Earth's atmosphere is stratified into troposphere, stratosphere, mesosphere, thermosphere, and exosphere; the ozone layer discovered through campaigns led by researchers engaged with World Meteorological Organization and United Nations Environment Programme mitigates ultraviolet flux from the Sun. Climate systems are influenced by circulation patterns like the Hadley cell, ocean-atmosphere interactions exemplified by El Niño–Southern Oscillation and Gulf Stream, and anthropogenic drivers documented in reports by the Intergovernmental Panel on Climate Change and studies published in venues such as Nature (journal) and Science (journal). Paleoclimatology uses proxies from sites like Greenland ice sheet cores and Vostok (Antarctica) records to study ice ages and warming events, with policy responses debated in forums like the United Nations Framework Convention on Climate Change and treaties following the Kyoto Protocol and the Paris Agreement.

Biosphere and Ecosystems

Biodiversity on Earth ranges from microorganisms cataloged by institutions such as the Smithsonian Institution to megafauna studied in regions like the Amazon Rainforest, Congo Basin, and Great Barrier Reef. Ecosystems include forests, grasslands, freshwater systems like the Amazon River and Caspian Sea, and marine systems such as the Sargasso Sea and abyssal plains studied by expeditions like those of Challenger (1872–1876) and research vessels from National Oceanic and Atmospheric Administration. Evolutionary theory advanced through work linked to Charles Darwin, Alfred Russel Wallace, and molecular studies in laboratories at institutions like Cold Spring Harbor Laboratory and Max Planck Society. Conservation efforts involve organizations such as World Wildlife Fund, Convention on Biological Diversity, and protected areas like Yellowstone National Park and Great Barrier Reef Marine Park.

Human History and Civilization

Humanity's prehistoric migrations are traced by archaeologists using evidence from sites like Çatalhöyük, Stonehenge, and Lascaux caves and genetic studies connected to populations across Eurasia, Africa, and Oceania. Ancient civilizations include the Mesopotamian civilization, Ancient Egypt, Indus Valley Civilization, Shang dynasty, Maya civilization, and empires such as the Roman Empire and Mongol Empire. Technological revolutions—Neolithic, Industrial, and Digital—are tied to innovations from figures and institutions including James Watt, Alexander Graham Bell, Alan Turing, and companies like IBM and Bell Labs. Global events shaping modern geopolitics include the Treaty of Westphalia, American Revolution, French Revolution, World War I, World War II, the Cold War, and diplomatic forums like the United Nations and European Union. Economic systems interact via institutions such as the International Monetary Fund and World Bank; cultural exchange followed routes like the Silk Road and maritime networks including the Age of Discovery linked to navigators like Christopher Columbus and Ferdinand Magellan.

Culture, Mythology, and Language

Human cultures express cosmologies referencing deities and myths such as Zeus, Thor, Viracocha, Pachamama, and Gaia, and literary works including the Epic of Gilgamesh, Iliad, Mahabharata, and Kojiki. Linguistic diversity spans families like Indo-European languages, Sino-Tibetan languages, Afro-Asiatic languages, and Niger–Congo languages, with scripts such as Cuneiform, Egyptian hieroglyphs, Chinese characters, and Latin alphabet evolving in contexts like Achaemenid Empire administration and the spread of Islam and Christianity. Artistic traditions range from cave paintings at Lascaux to Renaissance works by Leonardo da Vinci and Michelangelo, to modern movements represented in collections at the Louvre and Museum of Modern Art.

Exploration and Observation

Systematic observation of Earth combines astronomy, cartography, and remote sensing. Seafarers like Ferdinand Magellan and cartographers such as Gerardus Mercator expanded geographic knowledge, while satellites launched by agencies like NASA, ESA, Roscosmos, ISRO, and CNSA provide data for missions including Landsat, Sentinel series, GOES, and Copernicus Programme. Human spaceflight milestones—Sputnik 1, Vostok 1, Apollo 11, International Space Station—have enabled Earth observation and comparative planetology with studies of Mars Reconnaissance Orbiter and Cassini–Huygens. Modern geoscience integrates datasets maintained by the Global Seismographic Network, NOAA National Centers for Environmental Information, and initiatives like the Group on Earth Observations.

Category:Planets