Earth, the third planet from the Sun, is the only known celestial body to sustain life.

Formation

The oldest material found in the Solar System is dated to 4.5682 Ga (billion years) ago. By 4.54±0.04 Ga the primordial Earth had formed. The bodies in the Solar System formed and 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, and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides). According to nebular theory, planetesimals formed by accretion, with the primordial Earth being estimated as likely taking anywhere from 70 to 100 million years to form.

After formation

Earth's atmosphere and oceans were formed by volcanic activity and outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets, and comets. Sufficient water to fill the oceans may have been on Earth since it formed. 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 Ga, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind.

Countries

1. Africa
   1. Egypt
   2. Morocco
2. Asia
   1. China
   2. Japan
3. Europe
   1. France
   2. Germany
   3. United Kingdom
   4. Netherlands

World

• Africa
  • Northern Africa
    • Egypt
    • Morocco
    • Algeria
    • Tunisia
  • Sub-Saharan Africa
  • Central Africa
• Asia
• Europe
• North America
• South America
• Oceania

Natural history

Formation

The oldest material found in the Solar System is dated to 4.5682 Ga (billion years) ago.

After formation

Earth's atmosphere and oceans were formed by volcanic activity and outgassing.

Origin of life and evolution

Chemical reactions led to the first self-replicating molecules about four billion years ago.

Earth's expected long-term future is tied to that of the Sun. Over the next 1.1 billion years, solar luminosity will increase by 10%, and over the next 3.5 billion years by 40%. Earth's increasing surface temperature will accelerate the inorganic carbon cycle, possibly reducing CO2 concentration to levels lethally low for current plants (10 ppm for C4 photosynthesis) in approximately 100–900 million years.