Earth

Third planet of the star "Sol" (as named by its inhabitants)

## Description

Earth is the third planet from Sol, and the densest and fifth-largest of the eight planets in the Sol System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet, or by its Latin name, Terra. Its astronomical symbols are ⊕ and ♁.

Earth formed 4.54 billion years ago, and life appeared on its surface within one billion years. The planet is home to millions of species, including humans. Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful solar radiation, permitting life on land. The physical properties of the Earth, as well as its geological history and orbit, have allowed life to persist during this period. Estimates on how much longer the planet will to be able to continue to support life range from a mere 500 million years, to as long as 2.3 billion years.

Earth's outer surface is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods of many millions of years. About 71% of the surface is covered by salt water oceans, with the remainder consisting of continents and islands which together have many lakes and other sources of water that contribute to the hydrosphere. Earth's poles are mostly covered with solid ice (Antarctic ice sheet) or sea ice (Arctic ice cap). The planet's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.

Earth interacts with other objects in space, especially Sol and Luna At present, Earth orbits Sol once every 366.26 times it rotates about its own axis, which is equal to 365.26 solar days, or one sidereal year. The Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days). Earth's only known natural satellite, Luna which began orbiting it about 4.53 billion years ago, provides ocean tides, stabilizes the axial tilt, and gradually slows the planet's rotation. Between approximately 3.8 billion and 4.1 billion years ago, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment.

## History

4.5 Billion Years Ago - Earth formed from the remains of the formation of its star Sol, and back then Earth was hell during it’s first period in it’s history called The Hadean and then a Mars-sized planet known as Theia crashed into earth and formed Luna which we see in the night sky.

3.9 Billion Years Ago - The Late Heavy bombardment begins and Earth was hit by thousands of comets and asteroids, which helped to form the oceans. Some of the comets and asteroids hit the Moon which formed the craters on the Moon today.

3.8 Billion Years Ago - The very first sign of life on Earth arose in the form of microscopic cyanobacteria and other similar organisms, which helped create oxygen, which will then be used by multicellular organisms for respiration in the far far future.

650 Million Years Ago - The Earth was covered by a lot of snow and ice which was called by scientists of today known as The Snowball Earth, which is the coldest era/ice age of Earth’s history which, in coincidence, help multicellular life exist.

540 Million Years Ago - The very first multicellular life emerges which was called the Cambrian Explosion, where the very first animals emerged, which originated from the oceans of the Earth.

300 Million Years Ago - Earth has now entered the Carboniferous period where reptiles and insects now begin to evolve and where oxygen levels are now very high thanks to plants that take in carbon dioxide for photosynthesis and release oxygen as a waste chemical.

250 Million Years Ago - The end of the Palaeozoic era of Earth’s history, where Earth has entered the Permian era which had one of the largest mass extinctions in the Earth’s history, also know as the Great Dying, which killed off 95% of all life on earth and gave rise to the Mesozoic era.

230 Million Years Ago - Around 20 million years after the Great Dying the dinosaurs emerged out of the dust of the Great Dying event and Earth began to calm for the dinosaurs they are out beating the mammal like reptiles and other creatures to be the ultimate lifeforms of planet Earth and they would dominate Earth for 180 million years.

175 Million Years Ago - The supercontinent Pangaea began to brake apart which will form into the continents of today.

66 Million Years Ago - The dinosaurs were still the dominant rulers of earth and have survived the break-up of the supercontinent. They also survived the Triassic-Jurassic extinction event. They were nearly invincible until an asteroid the size of Mount Everest smacked into the Earth and caused the K-Pg mass extinction event, which killed off the herbivorous and carnivorous dinosaurs and 70% of all life on planet Earth, but still, some dinosaurs were still alive, and they evolved into the birds that we see today.

2 Million Years Ago - The very first humans emerged which were our ancestors who helped make fire that we could control and our ancestors also made cave paintings and the first ever writing.

Today - There are over 8 billion people on Earth at this time, we may have the chance to venture out to other star systems, planets and exoplanets and become an interstellar species for generations.

1. ↑ This section was adapted from Space Engine's ingame wiki