The planet earth is positioned in the 3rd place in our solar system , in orbit around the sun between Venus and Mars, that is, 149,600,000 km from the star king. It is the category of terrestrial systems is the largest and most dense and the fifth in size of the existing eight. Furthermore, it is the only planet in the system capable of supporting organic life as we know it.

Its name comes from ancient Roman mythology, terra: incarnation, of a primordial goddess who was related to femininity, fertility and the birth of most things. It is linked to motherhood in various cultures, such as the Pachamanca of the Incas or Western Mother Earth.

The earth has a single natural satellite that we call the moon, orbiting just 384,000 km from the surface. Our natural satellite is the fourth largest in the solar system and measures a quarter of the earth.

Birth and formation of the earth

The origin of the earth, like the other planets of the solar system is in the solar nebula, a disk of remnant matter from the constitution of the sun itself. It is estimated that 4,550 million years ago the earth already existed , after a period of cooling and composition of approximately 10 to 20 million years, as a result the outer layers of the earth system and the moon were created, due to the impact between a body roughly the size of Mars with Earth about 4.53 billion years ago.

This was followed by a gradual degassing of the planet’s crust, which joined the incipient volcanic activity, giving rise to the chemical processes that would result in the earth’s surface. Similarly, the appearance of water from the oceans, a prelude to life, this thanks to the introduction of ice and liquid water in comets, protoplanets and asteroids that collided with the young earth.

Earth movements

The earth carries out different movements: rotation, translation and obliquity.

• Rotation: the earth rotates around its axis, only in a west-east direction, and it takes 23 hours, 56 minutes and 4 seconds to contemplate a turn. This movement is of utmost importance since it allows day and night, alternating between the exposed and hidden face of the sun.
• Translation: the Earth’s orbit around the sun has a perimeter of 930 million kilometers, traveling at a speed of 108,000 kilometers per hour. That is, a complete orbital revolution takes place every 350 days, 5 hours, 48 ​​minutes and 45 seconds. This period is what we commonly classify as a year.
• Obliquity: the earth has an inclination in the plane of its elliptical of a little more than 23, and thanks to this the seasons of the year are given, since it basically brings certain planetary latitudes closer and further away from the sun. This movement is decreasing at a rate of 0.47 ”per year.

Atmosphere of earth

The balls of gases that surround the earth’s surface, prey to its force of gravity, are classified as the atmosphere. It is made up of 78% nitrogen, 21% oxygen , and the remaining noble gases and spreads from the earth’s surface up to about 11km high (75% of its content). Although, there are no definite limits to the atmosphere, as it begins at some point to fade into space. It is important to note that thanks to the amount of oxygen that exists on earth, life on the planet is possible.

Climatic phenomena are due to atmospheric nature and the redistribution of thermal energy, as well as the appearance of the ozone layer, which is extremely important and indispensable for the preservation of life by protecting it from the direct impact of UV radiation from the Sun.

Examples of planets more similar to the earth

• Kepler-438b
• Kepler-442b

Both orbit red dwarf stars that are smaller and cooler than our Sun. Kepler-438b orbits its star every 35 days, while Kepler-442b completes one orbit every 112 days.