Earth

Question

This piglix contains articles or sub-piglix about Earth

Answer 1

Anywhere on Earth

Anywhere on Earth (AoE) is a calendar designation which indicates that a period expires when the date passes everywhere on Earth. The last place on Earth where any date exists is on Howland Island, in the IDLW time zone (the "Hawaii side" of the International Date Line), and so is the last spot on the globe for any day to exist. Therefore, the day ends AoE when it ends on Howland Island.

The convention originated in IEEE 802.16 balloting procedures. At this point, many IEEE 802 ballot deadlines are established as the end of day using "AoE", for "Anywhere on Earth." as a designation. This means that the deadline has not passed if, anywhere on Earth, the deadline date has not yet passed.

Note that the day's end AoE occurs at noon Coordinated Universal Time (UTC) of the following day, Howland Island being halfway around the world from the Prime Meridian that is the base reference longitude for UTC.

Thus, in standard notation this is:

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Answer 2

Asteroid impact avoidance

Asteroid impact avoidance comprises a number of methods by which near-Earth objects (NEO) could be diverted, preventing destructive impact events. A sufficiently large impact by an asteroid or other NEOs would cause, depending on its impact location, massive tsunamis, multiple firestorms and an impact winter caused by the sunlight-blocking effect of placing large quantities of pulverized rock dust, and other debris, into the stratosphere.

A collision between the Earth and an approximately 10-kilometre-wide object 66 million years ago is thought to have produced the Chicxulub Crater and the Cretaceous–Paleogene extinction event, widely held responsible for the extinction of the dinosaurs.

While the chances of a major collision are not great in the near term, there is a high probability that one will happen eventually unless defensive actions are taken. Recent astronomical events—such as the Shoemaker-Levy 9 impacts on Jupiter and the 2013 Chelyabinsk meteor along with the growing number of objects on the Sentry Risk Table—have drawn renewed attention to such threats. NASA warns that the earth is unprepared.

Most deflection efforts for a large object require from a year to decades of warning, allowing time to prepare and carry out a collision avoidance project, as no known planetary defense hardware has yet been developed. It has been estimated that a velocity change of just 3.5/t × 10^−2 m·s^−1 (where t is the number of years until potential impact) is needed to successfully deflect a body on a direct collision trajectory. In addition, under certain circumstances, much smaller velocity changes are needed. For example, it was estimated there was a high chance of 99942 Apophis swinging by Earth in 2029 with a 10^−4 probability of passing through a 'keyhole' and returning on an impact trajectory in 2035 or 2036. It was then determined that a deflection from this potential return trajectory, several years before the swing-by, could be achieved with a velocity change on the order of 10^−6 ms^−1.

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Answer 3

Day length fluctuations

The length of the day, which has increased over the long term of Earth's history due to tidal effects, is also subject to change on a shorter scale of time. Exact measurements of time by atomic clocks and satellite laser ranging have revealed that the length of day (LOD) is subject to a number of different fluctuations. These tiny fluctuations have periods which range from a few weeks to a few years. They are attributed to interactions between the dynamic atmosphere and Earth itself. The International Earth Rotation and Reference Systems Service monitors the changes.

In the absence of external torques, the total angular momentum of Earth as a whole system must be constant. Internal torques are due to relative movements and mass redistribution of Earth's core, mantle, crust, oceans, atmosphere, and cryosphere. In order to keep the total angular momentum constant, a change of the angular momentum in one region must necessarily be balanced by angular momentum changes in the other regions.

Crustal movements (such as continental drift) or polar cap melting are slow secular events. The characteristic coupling time between core and mantle has been estimated to be on the order of ten years, and the so-called 'decade fluctuations' of Earth's rotation rate are thought to result from fluctuations within the core, transferred to the mantle. The length of day (LOD) varies significantly even for time scales from a few years down to weeks (Figure), and the observed fluctuations in the LOD - after eliminating the effects of external torques - are a direct consequence of the action of internal torques. These short term fluctuations are very probably generated by the interaction between the solid Earth and the atmosphere.

Any change of the axial component of the atmospheric angular momentum (AAM) must be accompanied by a corresponding change of the angular momentum of Earth's crust and mantle (due to the law of conservation of angular momentum). Because the moment of inertia of the system mantle-crust is only slightly influenced by atmospheric pressure loading, this mainly requires a change in the angular velocity of the solid Earth; i.e., a change of LOD. The LOD can presently be measured to a high accuracy over integration times of only a few hours, and general circulation models of the atmosphere allow high precision determination of changes in AAM in the model. A comparison between AAM and LOD shows that they are highly correlated. In particular, one recognizes an annual period of LOD with an amplitude of 0.34 milliseconds, maximizing on February 3, and a semiannual period with an amplitude of 0.29 milliseconds, maximizing on May 8, as well as 10‑day fluctuations of the order of 0.1 milliseconds. Interseasonal fluctuations reflecting El Niño events and quasi-biennial oscillations have also been observed. There is now general agreement that most of the changes in LOD on time scales from weeks to a few years are excited by changes in AAM.

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Answer 4

Demographics of the world

Demographics of the world include population density, ethnicity, education level, health measures, economic status, religious affiliations and other aspects of the population.

The overall total population of the world is approximately 7.45 billion, to July 2016.

Its overall population density is 50 people per km² (129.28 per sq. mile), excluding Antarctica. Nearly two-thirds of the population lives in Asia and is predominantly urban and suburban, with more than 2.5 billion in the countries of China and India combined. The World's fairly low literacy rate (83.7%) is attributable to impoverished regions. Extremely low literacy rates are concentrated in three regions, the Arab states, South and West Asia, and Sub-Saharan Africa. Christianity, Islam, Hinduism and Buddhism are the four largest religions encompassing a little over 75% of the populace.

The world's largest ethnic group is Han Chinese. Although English (5.52%) is spoken by many as a second language, Mandarin Chinese (14.1%) and Spanish (5.85%) are the languages with the highest number of native speakers.

Human migration has been shifting toward cities and urban centers, with the urban population jumping from 29% in 1950, to 50.5% in 2005. Working backwards from the United Nations prediction that the world will be 51.3 percent urban by 2010, Dr. Ron Wimberley, Dr. Libby Morris and Dr. Gregory Fulkerson estimated May 23, 2007 to be the first time the urban population outnumbered the rural population in history.China and India are the most populous countries, as the birth rate has consistently dropped in developed countries and until recently remained high in developing countries. Tokyo is the largest urban conglomeration in the world.

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Answer 5

Earth in culture

The cultural perspective on the Earth, or world, varies by society and time period. Religious beliefs often include a creation belief as well as personification in the form of a deity. The exploration of the world has modified many of the perceptions of the planet, resulting in a viewpoint of a globally integrated ecosystem. Unlike the remainder of the planets in the Solar System, mankind didn't perceive the Earth as a planet until the sixteenth century.

Unlike the other planets in the Solar System, in English, Earth does not directly share a name with an ancient Roman deity. The name Earth derives from the eighth century Anglo-Saxon word erda, which means ground or soil. It became eorthe later, and then erthe in Middle English. These words are all cognates of Jörð, the name of the giantess of Norse myth. Earth was first used as the name of the sphere of the Earth in the early fifteenth century. The planet's name in Latin, used academically and scientifically in the West during the Renaissance, is the same as that of Terra Mater, the Roman goddess, which translates to English as Mother Earth.

The standard astronomical symbol of the Earth consists of a cross circumscribed by a circle. This symbol is known as the wheel cross, sun cross, Odin's cross or Woden's cross. Although it has been used in various cultures for different purposes, it came to represent the compass points, earth and the land. Another version of the symbol is a cross on top of a circle; a stylized globus cruciger that was also used as an early astronomical symbol for the planet Earth.

Earth has often been personified as a deity, in particular a goddess. In many cultures the mother goddess is also portrayed as a fertility deity. To the Aztec, Earth was called Tonantzin—"our mother"; to the Incas, Earth was called Pachamama—"mother earth". The Chinese Earth goddess Hou Tu is similar to Gaia, the Greek goddess personifying the Earth. To Hindus it is called Bhuma Devi, the Goddess of Earth. (See also Graha.) In Norse mythology, the Earth giantess Jörð 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.

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Answer 6

Earth religion

Earth religion is a term used mostly in the context of neopaganism.

Earth-centered religion or nature worship is a system of religion based on the veneration of natural phenomena. It covers any religion that worships the earth, nature, or fertility gods and goddesses, such as the various forms of goddess worship or matriarchal religion. Some find a connection between earth-worship and the Gaia hypothesis. Earth religions are also formulated to allow one to utilize the knowledge of preserving the earth.

According to Marija Gimbutas, pre-Indo-European societies lived in small-scale, family-based communities that practiced matrilineal succession and goddess-centered religion where creation comes from the woman. She is the Divine Mother who can give life and take it away. In Irish mythology she is Danu, in Slavic mythology she is Mat Zemlya, and in other cultures she is Pachamama, Ninsun, Terra Mater, Nüwa, Matres or Shakti.

In the late 1800s, James Weir wrote an article describing the beginnings and aspects of early religious feeling. According to Boyer, early man was forced to locate food and shelter in order to survive, while constantly being directed by his instincts and senses. Because man's existence depended on nature, men began to form their religion and beliefs on and around nature itself. It is evident that man's first religion would have had to develop from the material world, he argues, because man relied heavily on his senses and what he could see, touch, and feel. In this sense, the worship of nature formed, allowing man to further depend on nature for survival.

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Answer 7

Earth%27s energy budget

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Answer 8

Earth%27s internal heat budget

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Answer 9

Geothermal energy

Geothermal energy is heat energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain but possibly roughly equal proportions). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface. The adjective geothermal originates from the Greek roots γη (ge), meaning earth, and θερμος (thermos), meaning hot.

Earth's internal heat is thermal energy generated from radioactive decay and continual heat loss from Earth's formation. Temperatures at the core–mantle boundary may reach over 4000 °C (7,200 °F). The high temperature and pressure in Earth's interior cause some rock to melt and solid mantle to behave plastically, resulting in portions of mantle convecting upward since it is lighter than the surrounding rock. Rock and water is heated in the crust, sometimes up to 370 °C (700 °F).

From hot springs, geothermal energy has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but it is now better known for electricity generation. Worldwide, 11,700 megawatts (MW) of geothermal power is online in 2013. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications in 2010.

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Answer 10

Earth in science fiction

An overwhelming majority of fiction is set on or features the Earth. However, authors of speculative fiction novels and writers and directors of science fiction film deal with Earth quite differently from authors of conventional fiction. Unbound from the same ties that bind authors of traditional fiction to the Earth, they can either completely ignore the Earth or use it as but one of many settings in a more complicated universe, exploring a number of common themes through examining outsiders perceptions of and interactions with Earth.

The overarching plot in both the original and re-imagined Battlestar Galactica is the quest to find Earth, which is thought to be the location of the lost thirteenth colony of Kobol. Colonial history dictates that Kobol is the homeworld of all humanity, and that the Thirteen Tribes of Kobol fled that world thousands of years earlier, with twelve tribes founding the Twelve Colonies and the thirteenth heading to Earth. Both shows are similar in that the location of Earth is initially unknown, but clues to its location are gradually discovered by the refugee fleet from the Twelve Colonies. In both series, the exodus of the Thirteen Tribes took place so far in the past that most modern Colonials have come to assume that the stories of Earth are simply religious myths.

In the original series, several clues indicate that the existence of Earth is real. On the prison planet of Proteus, Starbuck encounters drawings of star systems on the wall of a cell once occupied by a mysterious prisoner. The star charts turn out to be that of the Solar System. Additionally, when the Galactica later reaches a planet called Terra, it is inhabited by humans who use Earth units of measurement (hours, minutes, etc.) rather than Colonial units of measurement, suggesting that it was settled by members of the lost Thirteenth Tribe thousands of years earlier on their way to Earth.

In Galactica 1980, a continuation of the original series, the fleet did eventually discover Earth as it was in 1980.

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