Nuclear sharing is a concept in NATO's policy of nuclear deterrence, which involves member countries without nuclear weapons of their own in the planning for the use of nuclear weapons by NATO. In particular, it provides for the armed forces of those countries to be involved in delivering nuclear weapons in the event of their use; as part of nuclear sharing, the participating countries carry out consultations and make common decisions on nuclear weapons policy, maintain technical equipment required for the use of nuclear weapons and store nuclear weapons on their territory. In case of war, the United States told NATO allies the Non-Proliferation Treaty would no longer be controlling. Of the three nuclear powers in NATO, only the United States is known to have provided weapons for nuclear sharing; as of November 2009, Germany, the Netherlands and Turkey are hosting U. S. nuclear weapons as part of NATO's nuclear sharing policy. Canada hosted weapons under the control of the North American Aerospace Defense Command, rather than NATO, until 1984, having left the NATO program in 1972 and Greece until 2001.
The United Kingdom received U. S. tactical nuclear weapons such as nuclear artillery and Lance missiles until 1992 though the UK is a nuclear-weapon state in its own right. In peacetime, the nuclear weapons stored in non-nuclear countries are guarded by United States Air Force personnel and some nuclear artillery and missile systems were guarded by United States Army personnel. In case of war, the weapons are to be mounted on the participating countries' warplanes; the weapons are under custody and control of USAF Munitions Support Squadrons co-located on NATO main operating bases who work together with the host nation forces. As of 2005, 180 tactical B61 nuclear bombs of the 480 U. S. nuclear weapons believed to be deployed in Europe fall under the nuclear sharing arrangement. The weapons are stored within a vault in hardened aircraft shelters, using the USAF WS3 Weapon Storage and Security System; the delivery warplanes used are Panavia Tornados. The shared nuclear weapon delivery systems were not restricted to bombs.
Greece used Nike-Hercules Missiles as well as A-7 Corsair II attack aircraft. Canada had Bomarc nuclear-armed anti-aircraft missiles, Honest John surface-to-surface missiles and the AIR-2 Genie nuclear-armed air-to-air rocket, as well as tactical nuclear bombs for the CF-104 fighter. PGM-19 Jupiter medium range ballistic missiles were shared with Italian air force units and Turkish units with U. S. dual key systems to enable the warheads. PGM-17 Thor intermediate range. An extended version of nuclear sharing, the NATO Multilateral Force was a plan to equip NATO surface ships of the member states with UGM-27 Polaris missiles, but the UK ended up purchasing the Polaris missiles and using its own warheads, the plan to equip NATO surface ships was abandoned. After the Soviet Union collapsed, the nuclear weapon types shared within NATO were reduced to tactical nuclear bombs deployed by Dual-Capable Aircraft. According to the press, Eastern European Member States of NATO have resisted the withdrawal of the shared nuclear bombs from Europe, fearing it would show a weakening of U.
S. commitment to defend Europe against Russia. In Italy, B61 bombs are stored at the Aviano Air Base. According to the former Italian President Francesco Cossiga, Italy's plans of retaliation during the Cold War consisted of dropping nuclear weapons on Prague, Budapest and on all eastern countries in case of a first strike of the Soviets against NATO members, he acknowledged the presence of U. S. nuclear weapons in Italy, speculated about the possible presence of British and French nuclear weapons. The only German nuclear base is located near the border with Luxembourg; the base has 11 Protective Aircraft Shelters equipped with WS3 Vaults for storage of nuclear weapons, each with a maximum capacity of 44 B61 nuclear bombs. There are 20 B61 bombs stored on the base for delivery by German PA-200 Tornado IDS bombers of the JaBoG 33 squadron. By 2024 Germany's Tornado IDS aircraft are due to be retired, it is unclear what nuclear sharing role, if any, Germany will retain. On 10 June 2013, former Dutch prime minister Ruud Lubbers confirmed the existence of 22 shared nuclear bombs at Volkel Air Base.
Due to increasing risks some suggest moving nuclear weapons out of Turkey. Current: B61 nuclear bomb Former: AIR-2 Genie B57 nuclear bomb B28 nuclear bomb B43 nuclear bomb B61 nuclear bomb BGM-109G Ground Launched Cruise Missile CIM-10 Bomarc Mark 7 nuclear bomb Mk 101 Lulu MGR-1 Honest John MGM-1 Matador MGM-5 Corporal MGM-29 Sergeant MGM-52 Lance MIM-14 Nike Hercules Pershing 1 Pershing 1a PGM-17 Thor PGM-19 Jupiter UGM-27 Polaris W33 and W48 Artillery Shells It is common belief among f
The African Union is a continental union consisting of 55 member states located on the continent of Africa, with exception of various territories of European possessions located in Africa. The bloc was founded on 26 May 2001 in Addis Ababa and launched on 9 July 2002 in South Africa; the intention of the AU is to replace the Organisation of African Unity, established on 25 May 1963 in Addis Ababa by 32 signatory governments. The most important decisions of the AU are made by the Assembly of the African Union, a semi-annual meeting of the heads of state and government of its member states; the AU's secretariat, the African Union Commission, is based in Addis Ababa. The African Union has an area of around 29 million km2 and includes popular world landmarks, including the Sahara and the Nile; the primary languages spoken include Arabic, English and Portuguese and the languages of Africa. Within the African Union, there are official bodies such as the Peace and Security Council and the Pan-African Parliament.
The objectives of the AU are the following: To achieve greater unity and solidarity between the African countries and African nations. To defend the sovereignty, territorial integrity and independence of its Member States. To accelerate the political and social-economic integration of the continent. To promote and defend African common positions on issues of interest to the continent and its peoples. To encourage international cooperation, taking due account of the Charter of the United Nations and the Universal Declaration of Human Rights. To promote peace and stability on the continent. To promote democratic principles and institutions, popular participation and good governance. To promote and protect human and peoples' rights in accordance with the African Charter on Human and Peoples' Rights and other relevant human rights instruments. To establish the necessary conditions which enable the continent to play its rightful role in the global economy and in international negotiations. To promote sustainable development at the economic and cultural levels as well as the integration of African economies.
To promote co-operation in all fields of human activity to raise the living standards of African peoples. To coordinate and harmonise the policies between the existing and future Regional Economic Communities for the gradual attainment of the objectives of the Union. To advance the development of the continent by promoting research in all fields, in particular in science and technology. To work with relevant international partners in the eradication of preventable diseases and the promotion of good health on the continent; the African Union is made up of both administrative bodies. The highest decision-making organ is the Assembly of the African Union, made up of all the heads of state or government of member states of the AU; the Assembly is chaired by President of Egypt. The AU has a representative body, the Pan African Parliament, which consists of 265 members elected by the national legislatures of the AU member states, its president is Roger Nkodo Dang. Other political institutions of the AU include: the Executive Council, made up of foreign ministers, which prepares decisions for the Assembly.
The AU Commission, the secretariat to the political structures, is chaired by Nkosazana Dlamini-Zuma of South Africa. On 15 July 2012, Ms. Dlamini-Zuma won a contested vote to become the first female head of the African Union Commission, replacing Jean Ping of Gabon. Other AU structures are hosted by different member states: the African Commission on Human and Peoples' Rights is based in Banjul, the Gambia; the AU's first military intervention in a member state was the May 2003 deployment of a peacekeeping force of soldiers from South Africa and Mozambique to Burundi to oversee the implementation of the various agreements. AU troops were deployed in Sudan for peacekeeping during Darfur conflict, before the mission was handed over to the United Nations on 1 January 2008 UNAMID; the AU has sent a peacekeeping mission to Somalia, of which the peacekeeping troops are from Uganda and Burundi. The AU has adopted a number of important new documents establishing norms at continental level, to supplement those in force when it was created.
These include the African Union Convention on Preventing and Combating Corruption, the African Charter on Democracy and Governance, the New Partnership for Africa's Development and its associated Declaration on Democracy, Political and Corporate Governance. The historical foundations of the African Union originated in the First Congress of Independence African States, held in Accra, from 15 to 22 April 1958; the conference aimed at forming the Africa Day, to mark the liberation movement each year concerning the willingness of the African people to free themselves from foreign dictatorship, as well as subsequent attempts to unite Africa, including the Organisation of African Unity, established on 25 May 1963, the African Economic Community in 1981. Critics argued that the OAU in particular did little to protect the rights and liberties of African citizens from their own political leaders dubbing it the "Dictators' Club"; the idea of creating the AU was revived in the mid-1990s under the leadership of Libyan head of state Muammar al-Gaddafi: the heads of state and government of the OAU issued the Sirte Declara
New states of Germany
The new federal states of Germany are the five re-established states in the former East Germany that acceded to the Federal Republic of Germany with its 10 states upon German reunification on 3 October 1990. The new states, which were dissolved by the East German government in 1952 and were re-established in 1990, are Brandenburg, Mecklenburg-Vorpommern, Saxony-Anhalt and Thuringia; the state of Berlin, the result of a merger between East and West Berlin, is not considered one of the new states, although many of its residents are former East Germans. Since the reunification, Germany thus consists of 16 states with equal legal statuses, yet the process of the "inner reunification" between the former East and West Germany is still ongoing. Persisting differences in culture and mentality among the old East Germany and old West Germany are referred to as the "wall in the head". "Ossis" are stereotyped as racist and influenced by Russian culture. "Wessis" are considered snobbish, dishonest and selfish.
The terms can be considered disparaging. In 2009, twenty years after the fall of the wall, a poll found that 22% of former East Germans considered themselves "real citizens of the Federal Republic". 62% feel in a kind of limbo, no longer citizens of East Germany but not integrated into the unified Germany. Around 11% would have liked to have East Germany back. A 2004 poll found that 25% of West Germans and 12% of East Germans wished reunification had not happened; some East German brands have been revived, appealing to former East Germans who are nostalgic for the goods they grew up with. Brands revived in this manner include Rotkäppchen, which holds about 40% of the German sparkling wine market, Zeha, the sport shoe maker that supplied most of East Germany's sports teams and the Soviet Union national football team. Pornography and prostitution were outlawed in the GDR as forms of exploitation, West Germans believe that those who grew up in the GDR are more sexually inhibited than their western counterparts.
Nonetheless, better access to higher education and jobs along with free abortion and generous family policies made East German women more active sexually than before. Another notable difference is the attitude towards FKK in German. While it existed in both East and West, only in the East was it a mass cultural phenomenon in which everybody participated; this can still be seen at beaches of former East Germany compared to their West German counterparts. More children are born out of wedlock in eastern Germany than in western Germany. In 2009, in eastern Germany 61% of births were to unmarried women, while in western Germany 27% were; the states of Saxony-Anhalt and Mecklenburg-Western Pomerania had the highest rate of birth outside wedlock, each with 64%, followed by Brandenburg with 62%. The state of Baden-Württemberg had the lowest rate with 22%, followed by Hesse and Bavaria, each with 26%. Irreligion is predominant in the eastern part of Germany, considered to be the least religious region in the world.
An exception is former West Berlin, which had a Christian plurality in 2016. It has a higher share of Muslims, at 8.5%, compared to former East Berlin with only 1.5% self-declared Muslims as of 2016. On the other hand, Christianity is the dominant religion of Western Germany, excluding Hamburg, which has a non-religious plurality. On 26 April 2009, a referendum was held on whether Berlin pupils should be allowed to choose between the ethics class, a compulsory class introduced in all Berlin schools in 2006, a religion class; the SPD, the Left Party and Greens supported the "Pro Ethics" camp for a "No" vote, stressing that the ethics class should remain compulsory, pupils could voluntarily take an extra religion class alongside it if they so chose. In East Berlin, an overwhelming majority of 74.62% voted against the introduction of religious education. In West Berlin, only 41.41% voted "No". In total, 51.5% voted "No" and 48.4% voted "Yes". The economic reconstruction of eastern Germany is proving to be longer-term than foreseen.
The standard of living and average annual income remain lower in the new federal states. Reunification cost the federal government €2 trillion. At reunification all East German industry was considered outdated; the government privatised 8,500 state-owned East German enterprises. Since 1990, between €100 billion and €140 billion a year have been transferred to the new states. More than $60 billion were spent supporting businesses and building infrastructure in the years 2006-2008. A €156 billion economic plan, Solidarity Pact II, came into force in 2005, provides the financial basis for the advancement and special promotion of the economy of the new federal states until 2019; the "solidarity tax", a 5.5% surcharge on the income tax, was instated by the Kohl government to restore the infrastructure of the new states to the levels of the western ones and to apportion the cost of unification as well as the expenses of the Gulf War and of European integration. The tax, which raises €11 billion a year, will be maintained until 2019 at least.
Since reunification, the unemployment rate in the east has been twice that of the west. The unemployment rate reached 12.7% in April 2010, after having reached a maximum of 18.7% in 2005. In the decade 1999-2009, economic activity per person has risen from 67% to 71% of western Germany. According to Wolfgang Tiefensee, the minister responsible for the developme
A continent is one of several large landmasses of the world. Identified by convention rather than any strict criteria, up to seven regions are regarded as continents. Ordered from largest in area to smallest, they are: Asia, North America, South America, Antarctica and Australia. Geologically, the continents correspond to areas of continental crust that are found on the continental plates. However, some areas of continental crust are regions covered with water not included in the list of continents. Zealandia is one such area. Islands are grouped with a neighbouring continent to divide all the world's land into geopolitical regions. Under this scheme, most of the island countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form a geopolitical region called Oceania. By convention, "continents are understood to be large, discrete masses of land, ideally separated by expanses of water." Several of the seven conventionally recognized continents are not discrete landmasses separated by water.
The criterion "large" leads to arbitrary classification: Greenland, with a surface area of 2,166,086 square kilometres is considered the world's largest island, while Australia, at 7,617,930 square kilometres is deemed the smallest continent. Earth's major landmasses all have coasts on a single, continuous World Ocean, divided into a number of principal oceanic components by the continents and various geographic criteria; the most restricted meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term continental Europe is used to refer to mainland Europe, excluding islands such as Great Britain, Ireland and Iceland, the term continent of Australia may refer to the mainland of Australia, excluding Tasmania and New Guinea; the continental United States refers to the 48 contiguous states and the District of Columbia in central North America and may include Alaska in the northwest of the continent, while excluding Hawaii, Puerto Rico, Guam in the oceans.
From the perspective of geology or physical geography, continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area and the islands on the shelf, as they are structurally part of the continent. From this perspective, the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea together form a continent; as a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers group the Australian continental plate with other islands in the Pacific into one continent called Oceania; this divides the entire land surface of Earth into quasi-continents. The ideal criterion that each continent is a discrete landmass is relaxed due to historical conventions.
Of the seven most globally recognized continents, only Antarctica and Australia are separated from other continents by the ocean. Several continents are defined not as distinct bodies but as "more or less discrete masses of land". Asia and Africa are joined by the Isthmus of Suez, North and South America by the Isthmus of Panama. In both cases, there is no complete separation of these landmasses by water. Both these isthmuses are narrow compared to the bulk of the landmasses they unite. North America and South America are treated as separate continents in the seven-continent model. However, they may be viewed as a single continent known as America or the Americas; this viewpoint was common in the United States until World War II, remains prevalent in some Asian six-continent models. This remains the more common vision in Latin American countries, Portugal, Italy and Hungary where they are taught as a single continent; the criterion of a discrete landmass is disregarded if the continuous landmass of Eurasia is classified as two separate continents: Europe and Asia.
Physiographically and South Asia are peninsulas of the Eurasian landmass. However, Europe is considered a continent with its comparatively large land area of 10,180,000 square kilometres, while South Asia, with less than half that area, is considered a subcontinent; the alternative view—in geology and geography—that Eurasia is a single continent results in a six-continent view of the world. Some view separation of Eurasia into Asia and Europe as a residue of Eurocentrism: "In physical and historical diversity and India are comparable to the entire European landmass, not to a single European country.." However, for historical and cultural reasons, the view of Europe as a separate continent continues in several categorizations. If continents are defined as discrete landmasses, embracing all the contiguous land of a body Africa and Europe form a single continent which may be referred to as Afro-Eurasia; this produces a four-continent model consisting of Afro-Eurasia, America and Australia. When sea levels were lower during the Pleistocene ice ages, gre
Mauritius the Republic of Mauritius, is an island nation in the Indian Ocean. The main Island of Mauritius is located about 2,000 kilometres off the southeast coast of the African continent; the Republic of Mauritius includes the islands of Rodrigues, Agalega and St. Brandon; the capital and largest city Port Louis is located on the main island of Mauritius. In 1598, the Dutch took possession of Mauritius, they abandoned Mauritius in 1710 and the French took control of the island in 1715, renaming it Isle de France. France ceded Mauritius including all its dependencies to the United Kingdom through the Treaty of Paris, signed on 30 May 1814 and in which Réunion was returned to France; the British colony of Mauritius consisted of the main island of Mauritius along with Rodrigues, Agalega, St Brandon and the Chagos Archipelago, while the Seychelles became a separate colony in 1906. The sovereignty of Tromelin is disputed between Mauritius and France as some of the islands such as St. Brandon, Chagos and Tromelin were not mentioned in the Treaty of Paris.
In 1965, three years prior to the independence of Mauritius, the UK split the Chagos Archipelago from Mauritian territory, the islands of Aldabra and Desroches from the Seychelles, to form the British Indian Ocean Territory. The UK forcibly expelled the archipelago's local population and leased its largest island, Diego Garcia, to the United States; the UK has restricted access to the Chagos Archipelago. The sovereignty of the Chagos is disputed between Mauritius and the UK. In February 2019, in an advisory opinion given by the International Court of Justice on this dispute, the ICJ ordered the UK to hand back the Chagos Islands to Mauritius as as possible; the people of Mauritius are multiethnic and multilingual. The island's government is modelled on the Westminster parliamentary system, Mauritius is ranked for democracy and for economic and political freedom; the Human Development Index of Mauritius is one of the highest in Africa. Mauritius is ranked as the most competitive and one of the most developed economies in the African region.
The main pillars of the Mauritian economy are manufacturing, financial services and information and communications technology. Mauritius is a welfare state. Along with the other Mascarene Islands, Mauritius is known for its varied flora and fauna, with many species endemic to the island; the island was the only known home of the dodo, along with several other avian species, was made extinct by human activities shortly after the island's settlement. The first historical evidence of the existence of an island now known as Mauritius is on a map produced by the Italian cartographer Alberto Cantino in 1502. From this, it appears that Mauritius was first named Dina Arobi around 975 by Arab sailors, the first people to visit the island. In 1507, Portuguese sailors visited the uninhabited island; the island appears with a Portuguese name Cirne on early Portuguese maps from the name of a ship in the 1507 expedition. Another Portuguese sailor, Dom Pedro Mascarenhas, gave the name Mascarenes to the Archipelago.
In 1598, a Dutch squadron under Admiral Wybrand van Warwyck landed at Grand Port and named the island Mauritius, in honour of Prince Maurice van Nassau, stadholder of the Dutch Republic. The island became a French colony and was renamed Isle de France. On 3 December 1810, the French surrendered the island to Great Britain during the Napoleonic Wars. Under British rule, the island's name reverted to Mauritius. Mauritius is commonly known as Maurice and Île Maurice in French, Moris in Mauritian Creole; the island of Mauritius was uninhabited before its first recorded visit during the Middle Ages by Arab sailors, who named it Dina Arobi. In 1507, Portuguese sailors came to the uninhabited island and established a visiting base. Diogo Fernandes Pereira, a Portuguese navigator, was the first European known to land in Mauritius, he named the island "Ilha do Cirne". The Portuguese did not stay. In 1598 a Dutch squadron under Admiral Wybrand van Warwyck landed at Grand Port and named the island "Mauritius" after Prince Maurice of Nassau of the Dutch Republic.
The Dutch inhabited the island in 1638, from which they exploited ebony trees and introduced sugar cane, domestic animals and deer. It was from here; the first Dutch settlement lasted twenty years. Several attempts were subsequently made, but the settlements never developed enough to produce dividends, causing the Dutch to abandon Mauritius in 1710. France, which controlled neighbouring Île Bourbon, took control of Mauritius in 1715 and renamed it Isle de France. In 1723, the Code Noir was established to categorise one group of human beings as "goods", in order for the owner of these goods to be able to obtain insurance money and compensation in case of loss of his "goods"; the 1735 arrival of French governor Bertrand-François Mahé de La Bourdonnais coincided with development of a prosperous economy based on sugar production. Mahé de La Bourdonnais established Port Louis as a shipbuilding centre. Under his governorship, numerous buildings were erected, a number of which are sti
A military base is a facility directly owned and operated by or for the military or one of its branches that shelters military equipment and personnel, facilitates training and operations. A military base provides accommodations for one or more units, but it may be used as a command center, training ground or proving ground. In most cases, military bases rely on outside help to operate. However, certain complex bases are able to endure on their own for long periods because they are able to provide food and other life support necessities for their inhabitants while under siege. Military bases for military aviation are called military air bases. Military bases for military ships are called naval bases. Military bases within the United States are considered federal property and are subject to federal law. Civilians living on military bases are subject to the civil and criminal laws of the states where the bases are located. Military bases can range from small outposts to military cities containing up to 100,000 people.
Military bases may belong to a different state than the territory surrounding it. The name used refers to the type of military activity that takes place at the base. A military base may go by any of a number of names, such as the following: Depending on the context, the term'military base' may refer to any establishment that houses a nation's armed forces, or organized paramilitary forces such as the Police, Militia, or Guards. Alternatively, the term may refer to an establishment, used only by an army to the exclusion of a base used by either an air force or a navy; this is consistent with the different meanings of the word'military'. Some examples of permanent military bases used by the navies and air forces of the world are the HMNB Portsmouth in Portsmouth, UK, the Naval Air Station Whidbey Island, Washington State, USA, or Ramstein Air Base, Germany. Other examples of non- or semi-permanent military bases include a Forward Operating Base, a Logistics Base and a Fire Base. A military base may contain large concentrations of military supplies in order to support military logistics.
Most military bases are restricted to the public and only authorized personnel may enter them. In addition to the main military facilities on a certain installation, military bases have various different facilities for military personnel; these facilities vary from country to country. Military bases can provide housing for a post office and dining facilities, they may provide support facilities such as fast food restaurants, gas stations, schools, thrift stores, a hospital or clinic, movie theaters, retail stores. Family, Morale and Recreation provides facilities such as fitness centers, golf courses, Travel centers, Community service centers, child development centers, youth centers, automotive workshops, hobby/arts and crafts centers, bowling centers, community centers. Bases used by the United States Air Force Reserve tend to be active USAF bases. However, there are a few Air Reserve Bases, such as Dobbins ARB, Grissom ARB, both of which are former active-duty USAF bases. Facilities of the Air National Guard are located on civil airports in a secure cantonment area not accessible to the general public, though some units are based on USAF bases, a few ANG-operated bases, such as Selfridge ANGB, Michigan.
Support facilities on Air National Guard and Air Force Reserve installations tend to not be as extensive as active bases. As an examples, 1) the Russian Sevastopol Naval Base comprises individual facilities located within the city of Sevastopol proper as well as an airfield at Kacha north of the city. An overseas military base is a military base, geographically located outside of the territory of the country whose armed forces are the principal occupants of the base; the use of overseas military base has throughout its history of usage been a contentious issue of debate, is a source of opposition for antimilitarists and nationalists in the host country. Such bases may be established by treaties between the governing power in the host country and another country which needs to establish the military base in the host country for various reasons strategic and logistic. Furthermore, overseas military bases serve as the source of the military brat subculture due to the children of the bases' occupant military being born or raised in the host country but raised with a remote parental knowledge of the occupant military's home country.
In the 18th and 19th Centuries the Royal Eng
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times. Earth's axis of rotation is tilted with respect to its orbital plane; the gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, slows its rotation. Earth is the largest of the four terrestrial planets. Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water by oceans; the remaining 29% is land consisting of continents and islands that together have many lakes and other sources of water that contribute to the hydrosphere.
The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, a convecting mantle that drives plate tectonics. Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms; some geological evidence indicates. Since the combination of Earth's distance from the Sun, physical properties, geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely. Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.
Humans have developed diverse cultures. The modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most spelled eorðe, it has cognates in every Germanic language, their proto-Germanic root has been reconstructed as *erþō. In its earliest appearances, eorðe was being used to translate the many senses of Latin terra and Greek γῆ: the ground, its soil, dry land, the human world, the surface of the world, the globe itself; as with Terra and Gaia, Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus, Norse mythology included Jörð, a giantess given as the mother of Thor. Earth was written in lowercase, from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, the earth became the Earth when referenced along with other heavenly bodies. More the name is sometimes given as Earth, by analogy with the names of the other planets.
House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name but writes it in lowercase when preceded by the, it always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago. By 4.54±0.04 Bya the primordial Earth had formed. The bodies in the Solar System evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, dust. According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 million years to form. A subject of research is the formation of some 4.53 Bya. A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth.
In this view, the mass of Theia was 10 percent of Earth, it hit Earth with a glancing blow and some of its mass merged with Earth. Between 4.1 and 3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity. By 3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. A crust formed; the two models that explain land mass propose either a steady growth to the present-day forms or, more a rapid growth early in Earth history followed by a long-term steady continental area. Continents formed by plate tectonics