Earth

Earth is the Homeworld of Humanity.

**Location:** Milky Way Galaxy/Local Cavity/Solar System

**World Category:** Garden World

**Earth** is the third planet orbiting the Sun, the largest terrestrial planet in the Solar System and the only planet in the system with natural stable liquid water oceans on its surface. The planet is known to be the Homeworld of Humanity and hosting one of the most diverse ecosystems in the Milky Way Galaxy.

## Planetary Properties

### Geology

Earth was initially molten due to extreme volcanism and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as a result of the impact of a planetoid with the Earth. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered from comets, produced the oceans.

As the surface continually reshaped itself over hundreds of millions of years, continents formed and broke apart. They migrated across the surface, occasionally combining to form a supercontinent. Roughly 750 million years ago, the earliest-known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia, 600 to 540 million years ago, then finally Pangaea, which broke apart 200 million years ago.

The present pattern of ice ages began about 40 million years ago, then intensified at the end of the Pliocene. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000–100,000 years. The last glacial period of the current ice age ended about 10,000 years ago. Earth is now in an stable form of tectonic activity, and its active core producing a strong magnetic field, protecting the planet.

### Atmosphere

The atmospheric pressure at Earth's sea level averages 101.325 kPa or 14.696 psi also knows as 1.00 atm, with a scale height of about 8.5 km (5.3 mi). A dry atmosphere is composed of 78.068% nitrogen, 20.911% oxygen, 0.913% argon, and trace amounts of carbon dioxide and other gaseous molecules. Water vapor content averages about 1%. The height of the troposphere varies with latitude, ranging between 8 km (5 mi) at the poles to 17 km (11 mi) at the equator, with some variation resulting from weather and seasonal factors.

Earth's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 2.7 Gya, forming the primarily nitrogen–oxygen atmosphere of today. This change enabled the proliferation of aerobic organisms and, indirectly, the formation of the Ozone layer due to the subsequent conversion of atmospheric O2 into O3. The Ozone layer blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water Vapor, Carbon Dioxide, Methane, Nitrous Oxide, and Ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface temperature would be −18 °C, in contrast to the current +18 °C, and life on Earth probably would not exist or would be very different.

Earth's temperature has increased by a dramatic 4 °C in the past 300 years, but geo-engineering of the planet fueled by Helium-3 harvested from the gas giants of the system, specially Uranus, has stopped the negative impact of this phenomenon.

### Natural Satellite

* *Main Article: **Moon***

The Moon is a relatively large, terrestrial, planet-like natural satellite, with a diameter about one-quarter of Earth's. It is the 5th largest moon in the Solar System. The natural satellites of other planets are also referred to as "moons", after Earth's. The most widely accepted theory of the Moon's origin, the giant-impact hypothesis, states that it formed from the collision of a Mars-size protoplanet called Theia with the early Earth. This hypothesis explains (among other things) the Moon's relative lack of iron and volatile elements and the fact that its composition is nearly identical to that of Earth's crust.

## Biosphere

A planet's life forms inhabit ecosystems, whose total forms the biosphere. The biosphere is divided into a number of biomes, inhabited by broadly similar plants and animals. On land, biomes are separated primarily by differences in latitude, height above sea level and humidity. Terrestrial biomes lying within the Arctic or Antarctic Circles, at high altitudes or in extremely arid areas are relatively barren of plant and animal life; species diversity reaches a peak in humid lowlands at equatorial latitudes. Estimates of the number of species on Earth today vary; most species have not been described.

Earth supports billions of animal and plant life species on and sea, which make it one of the most diverse biospheres in the Galaxy. Human impact is felt in many areas due to pollution of the air and water, acid rain, loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, species extinction, soil degradation, soil depletion and erosion. There is a scientific consensus that humans are causing global warming by releasing greenhouse gases into the atmosphere. This is driving changes such as the melting of glaciers and ice sheets, a global rise in average sea levels, and significant shifts in weather.

## Humanity

### History

As early *Homo sapiens* (Current Humans) dispersed from their first homeland, it encountered varieties of archaic Humans both in Africa and in Eurasia. The "out of Africa" migration of *Homo sapiens* took place in two waves, the first 130,000 to 100,000 years ago, the second 70,000 to 50,000 years ago, resulting in the colonization of Australia 65–50,000 years ago. Modern Humans subsequently spread globally, replacing archaic Humans (through competition and hybridization). 50,000 years ago, and likely significantly earlier behavioral modernity, including language, music and other cultural universals had developed. They inhabited Eurasia and Oceania by 40,000 years ago, and the Americas at least 14,500 years ago.

The rise of agriculture, and domestication of animals, led to stable human settlements.

Until about 12,000 years ago, all Humans lived as hunter-gatherers, generally in small nomadic groups, often in caves. The invention of agriculture took place beginning about 10,000 years ago. Access to food surplus led to the formation of permanent Human settlements, the domestication of animals and the use of metal tools for the first time in history. Agriculture and sedentary lifestyle led to the emergence of early civilizations from about 5,000 years ago. The Scientific Revolution, Technological Revolution and the Industrial Revolution brought such discoveries as imaging technology, major innovations in transport, such as the airplane and automobile; and energy development such as electricity. With the advent of the Information Age at the end of the 20th century, modern humans lived in a world that had become increasingly globalized and interconnected. With the beginning of the new Space Age, Human began colonizing other bodies in their home system and finally expanding into other stars. Humans are now considered one of the most influential species in the Council Space.

### UNCA

* *Main Article: **United Nations Colonial Affairs***

United Nations Colonial Affairs or UNCA in short, was the first united Human agency to administrate Human efforts in outer space colonization and administration. It was established in 2041 following the decision to industrialize the Moon. UNCA gave it position to EUSI after Mars, the first Human civilian colony in another planet declared their independence.

### EUSI

* *Main Article: **Earth United Space Initiative***

**Earth United Space Initiative** or EUSI in short, is a Human alliance between the nations of Earth to protect Earth interest in outer space. It was established following the defeat of Earth security forces which was unprepared for a war in another planet and the fall of the only 2 planets under Earth control as of that year. EUSI has several branches overseeing Earth defense force, colonization of outer space, terraformation of celestial bodies and protecting Human interests following the First Contact War.

### The Federation

the Federation of the Solar System Planets of the Federation in short, is a Human military alliance between the intendent states of the Humanity home system. Its mission is to act as Humanity military, represents their home system in Unity and Council Space and coordinating Human efforts in colonizing other planets.