Earth is the Doctor's favorite planet, the twin planet of Mondas, located in the Sol system in Mutter's Spiral. Most of the Doctor's companions have been natives of this planet. It is the native planet of Humans, Silurians, Sea Devils and (possibly in an alternative timeline) Haemovores.
Astronomical Data
Location
Located in Sector 8023 of the Third Quadrant.(source?) Third planet in the Sol system, 1 AU from the Sun, approximately 27,700 light-years from the center of Mutter's Spiral. It was shifted two light years from this position by the Time Lords and renamed Ravolox circa 2,000,000 CE.)
Moon(s)
For most of its history, Earth had one single moon, usually referred to simply as the Moon, a rogue planet which entered the Sol system and was captured in Earth's gravitational field millions of years ago (DW: Doctor Who and the Silurians). By the time of the Fourth Great and Bountiful Human Empire, four other moons had been added to the Terran system. Whether these additional moons were artificially constructed or natural ones moved into Earth orbit is not known (DW: The Long Game).
Further Information
Sapient native species
Several sapient and semi-sapient species have evolved on Earth, though the most important and influential ones have been the Humans and Earth Reptiles.
Earth Reptiles
Human species
Others
Historical
Earth formed over 4 and a half billion years ago, around the same time as the first conflict between the Hoothi and the Time Lords (NA: Love and War), around a Racnoss spacecraft carrying the last remainders of their race (DW: The Runaway Bride). About 3 billion years ago, the consciousness of the Sou(ou)shi settled on Earth and became dormant, reawakening in the year 1968 (MA: Venusian Lullaby, NA: Nightshade). Life eventually developed due to the explosion of a Jagaroth spaceship (DW: City of Death).
Various species of saurian dominated the planet until circa 65 million BCE, when a freighter from the 2500s time-warped to this period and exploded in the upper atmosphere (DW: Earthshock). A few survived, evolving into the races later known as Silurians and Sea Devils. Another saurian race, of unknown name, predated these reptilian races by about 100,000 years (NA: All-Consuming Fire). The Reign of the Reptiles came to a final end when the rogue planet which later became the Moon entered Earth's orbit, creating climatic changes which forced the reptile races into underground hibernation. Apes regarded by the reptiles as pests eventually evolved into the species known as human, given a substantial jolt forward when the Fendahl Core arrived on Earth circa 12 million BCE (DW: Image of the Fendahl).
Human civilization evolved quickly, assisted by the Daemons, the various temporal fragments of Scaroth, and the predatory nature imparted to humans by the Fendahl. This predatory and aggressive nature was evident in the many conflicts which humans fought amongst themselves throughout much of their early history, such as during the siege of Troy, the Dark Ages, or the American War for Independence (DW: The Mark of the Rani). It was also exploited by the War Lords, who kidnapped human soldiers from various conflicts in Earth history for use in their war games (DW: The War Games).
Earth had been visited by aliens many times throughout its history, but the launching of space probes by humans beginning in the late 20th century made such visits more frequent, as Homo sapiens began drawing attention to themselves. These visits also tended to be more openly hostile, and Earth was saved from conquest or outright annihilation often only through the intercession of the Doctor. Such invasions also led to the formation of UNIT, whose functions in time culminated in the first conquest by Earth of an alien world, Mars, in 2086 (DW: Transit) .
Earth developed methods of faster then light travel in the late 21st century and began colonizing nearby star systems soon after. The 22nd century Dalek invasion proved devastating to Earth, with New York and many other cities destroyed and entire regions of Africa and South America depopulated. The expulsion of the Dalek force from Earth and the victorious Battle of Cassius saw the planet reborn. Humans reclaimed their old colonies and in time an Earth Empire emerged which dominated most of Mutter's Spiral for over 500 years. This empire at times came into conflict with other space powers, particularly the Draconians, and often employed oppressive and disenfranchising policies on numerous alien races, most notably on Delta Magna and Solos. Unrest among these races and instabilities in the Empire's political and economic structure eventually led to the dissolution of the Empire, which in time gave way to the Galactic Federation, headquartered on Io (NA: Legacy). By 4000, the Federation came under the control of Mavic Chen (DW: The Daleks' Master Plan) and his descendants, who eventually transformed the once democratic organization into a new version of the old Earth Empire (MA: The Crystal Bucephalus).
By the year 200,000, Earth was at its height, covered with megacities, five moons and a population of 96 billion. It was the centre of the galactic domain of the Fourth Great and Bountiful Human Empire that stretched across a million planets and species (DW: The Long Game).
Earth in its later history was abandoned numerous times by its human inhabitants, first when solar flares bombarded the planet, leaving Earth uninhabited for 10,000 years (DW: The Ark in Space). Although surviving humans who had slept aboard the Nerva beacon recolonized the planet, it was later occupied by the Chaarl, who renamed the world Antýkhon. Humans, referred to as "Hairies," managed to adapt to the depleted atmosphere and soil caused by the Chaarls' industrial activities. The Chaarl occupation lasted some 3497 years (NA: Birthright). Some time after, Earth was visited by the Usurians, who relocated the dying human population first to Mars and then Pluto. Generations later, humans had thrown off the yoke of Usurian exploitation, and returned to Earth (DW: The Sun Makers).
About 2,000,000, Earth was relocated two light-years from its proper position in the galaxy by the Time Lords to prevent the escape by aliens from Andromeda who had stolen information from the Matrix on Gallifrey. Most of the human race remaining on Earth were wiped out, and those that survived degenerated to a primitive, tribal culture. The planet came to be known as Ravolox, with Earth being completely forgotten (DW: The Mysterious Planet). The inhabitants of Ravolox eventually came to know of the true nature and history of their planet, and to rebuild their civilization.
Eventually, humans rediscovered space travel, and humans abandoned their planet for the last time, fleeing to worlds like Refusis II and Frontios (DW: The Ark, Frontios), when the Sun threatened to swallow the Earth in the 57th segment of time, a period originally estimated to be around the year 10,000,000, but now known to be closer to 5 billion, meaning the Earth lasted for approximately 9 and a half billion years. Up to that time, the National Trust had been using gravity satellites to hold back the expanding Sun. However, funds for the preservation of Earth had run out, and the gravity satellites were allowed to run down, so that the Sun finally achieved its long-delayed red giant stage and the Earth exploded into rubble, an event witnessed by select members of the great and the good (i.e., the rich) of the galaxy (DW: The End of the World). By then, humanity had spread throughout and beyond the Local Group, touching every star in the sky.
Political
Until well into the 3000s, Earth was divided into myriad nation-states of varying size, population, tactical strength, and socio-political, economic, and religious ideologies, all at any given time allied to or warring with each other. The first moves towards planetary union actually came in the form of military conquest and annexation of nations by leaders such as Alexander the Great and Julius Caesar, with the Old Roman Empire, the Han Empire of China, and the Great Khanates of the Mongols being among the earliest superpowers. From the 17th to the 22nd centuries, much of the military and economic strength of Earth was controlled by the British Empire, and France, and, later, the United States of America, a former colonial possession of Britain's, as well as the Soviet Union, later reformed as the Russian Federation, and China.
The earliest peaceful attempt at unifying the planet under one governing body was the formation of the League of Nations at the close of the First World War. The 1930s saw the formation of LONGBOW, an organisation set up under the umbrella of the League to handle matters of international security, occasionally running into threats of an extraterrestrial nature. While never made public, this was the first acknowledgement by the world's leaders that humans were not alone in the universe, and their neighbors were not always friendly. LONGBOW ceased operations after both it and the League failed to prevent the outbreak of the Second World War, when Adolf Hitler sent German troops on an invasion of Poland.
The United Nations was formed at the end of the Second World War, hoping to succeed where its predecessor had failed in preventing global conflict. After numerous alien attacks, especially those by the Yeti (DW: The Web of Fear) and the Mondasian Cybermen (DW: The Invasion), the UN at the suggestion of Colonel (later Brigadier) Alistair Gordon Lethbridge-Stewart, drew up the charter for UNIT, whose duty was essentially the same as LONGBOW's had been.
The development of nuclear weapons and the Cold War increased international tensions in the late 20th century. At numerous times, nuclear war seemed imminent. This threat was somewhat alleviated when the great powers entrusted their nuclear launch codes to the United Kingdom for safe-keeping (DW: Robot), when half of the planet came under the government of the World Zone Authority in the early 21st century (DW: The Enemy of the World) this often came into conflict with The New British Empire which was formed with the help of the Torchwood Institute. Tensions between the two empires returned again in the later half of the century. An end to these tensions did not arrive until the Martian assault of 2086, in which Paris was destroyed. A common, alien enemy united humans and planted the seeds for a united Earth (NA: Transit). A brief relapse into warring feudal states followed the Dalek occupation before the Earth was once again united under The New British Empire (EDA: Legacy of the Daleks). It was also around this time that Earth formed the Alliance with Alpha Centauri and other nearby systems, its first formal alliance with alien species (NA: Original Sin, MA: Lords of the Storm).
The united Earth government quickly became corrupt and on the payroll of powerful financial concerns like INITEC, the Galatron Mining Corporation, the AMORB Project, and especially IMC, looking the other way as these organizations victimized indigenous species and human colonists alike on the outer worlds (DW: Vengeance on Varos, Colony in Space). In time the business policies of these corporations and the political and diplomatic policies of the Earth government became parallel and laid the foundations for the Earth Empire. Law and order was enforced by the Adjudicators. Although Earth was governed by a democratically elected President who ruled under The New British Empire, civil liberties in the mid-third millennium were highly marginalized, and critics of the government were frequently sent to the Moon, which was converted from a civilian colony to a prison (DW: Frontier In Space). In the last centuries of the third millennium, the Presidency was transformed into an Imperial monarchy, with the Holy King (or Queen) ruling Earth and its empire. The last Holy Monarch left control of the Earth to a ruling council upon her death, shortly before the Solos Incident (NA: Original Sin, DW: The Mutants).
With the advent of the Second Ice Age and continuing unrest among the colonies, Earth's global government collapsed at the turn of the fourth millennium, and feudalism returned both on the planet and on many of its colonies. An aristocratic government remained in control of Earth when the Galactic Federation was formed in the later years of the millennium (DW: The Curse of Peladon). This aristocracy eventually gave way to more democratic forms, but this new era of freedom was short-lived as the Solar System came under the sway of the Chen Dynasty after 4000 (DW: The Daleks' Master Plan, MA: The Crystal Bucephalus). As the Chen focused more of their attention on the outer worlds, Earth once more broke up into rival nation states, with a Sixth World War looming by the year 5000 between the superpowers of Iceland, the Philippines, and Australia (DW: The Talons of Weng-Chiang). The issue of international conflict became moot when humanity was forced to flee Earth before its bombardment by solar flares (DW: The Ark in Space).
Information on what forms of government existed on Earth during its later periods is scant, owing to the frequent evacuations and resettlements by humanity which occurred. During Earth's period as the planet Ravolox, the few surviving humans there appear to have lived in a tribal matriarchy somewhat similar to that of the ancient Celts (DW: The Mysterious Planet).
Geographical
Earth's surface has changed considerably over the course of its long history, owing to its high seismic activity. When native life first appeared on the planet, for example, what later became the middle of the Atlantic Ocean was a vast, rocky wasteland (DW: City of Death). What follows is a general description of what came to be known as "Earth Classic" (DW: The End of the World).
Through most of its history, two-thirds of the Earth's surface was covered by water. Several large land-masses were in existence. Changes to the topography were relatively frequent, owing to erosion and seismic and volcanic activity. Two particularly cataclysmic events occurred when Atlantis, already ravaged first by the Dæmons and then Kronos, sank beneath the waves circa 2000 BCE (DW: The Underwater Menace, The Dæmons, The Time Monster) and when Krakatoa erupted in 1883, the latter event being witnessed by both the Third and Ninth Doctors (DW: Inferno, Rose).
Over millions of years, continental drift caused the surface of Earth to change radically, creating such features as the Arctic Desert and the Los Angeles Crevasse. However, the same National Trust which installed gravity satellites to hold back the expanding Sun also shifted the continents back to their early positions, a planetary style known as Earth Classic. The Earth's surface remained in this state until the planet's final destruction in the 57th segment of time (DW: The End of the World).
People
Economy
Variations and hybrids of capitalism, communism, and socialism have been practiced by Earth humans throughout their history. No information is currently available on what economic forms were utilized by the reptilian species which preceded humans. Towards the end of Earth's history, Trees which traced their ancestry to the tropical rain forests had acquired sizable fortunes, mostly in real estate (DW: The End of the World).
Most Earth currency was decimalized by the 20th century, with Britain's monetary system becoming decimalized in 1971 (DW: An Unearthly Child).