Earth
Earth is the third planet of our Solar System and it is our home. A full circle around the Sun takes a year (about 365 days), while rotating around itself takes 24 hours. It is the only planet we know so far which host any form of life.
Its atmosphere consists of 78% nitrogen, 21% oxygen and 1% various other elements, where carbon dioxide, ozone and water are among them. Without an atmosphere, Earth would have an average temperature of -18 ° C and not 15 ° C that it normally does. Due to the inclination of its axis with respect to the ecliptic it presents seasonal fluctuations which are the seasons we know. Earth's temperature allows water to appear in all three states, ice, water and water vapor.
About 71% of its surface is below sea level and is covered by ocean water. Its continental part varies from place to place and consists mainly of mountains, deserts, plains and plateaus. The highest mountain is Everest which reaches 9km.
Its core is a solid iron-nickel core surrounded by a liquid outer core consisted of iron and nickel. The combination of this fluid conductive core and the planet’s rapid rotation creates a powerful magnetic field that protects its surface from life-threatening, solar wind. The outer casing is surrounded by a mantle consisting of sulfur compounds in a cumbersome fluid form, as hot asphalt. The currents created in the mantle are responsible for the movements of the next and last part of the crust on which we live. These movements are responsible for the movement of tectonic plates and earthquakes. The tectonic plates are submerged and re-created, resulting in a renewed surface of the planet.
Earth has one natural satellite, the Moon.
The Moon
The Moon is the only natural Earth satellite. Its radius is one-quarter of the Earth and its distance is 384.000 km, that is about the distance the light travels in a second. The Moon is a gravitationally locked satellite, meaning that the period of rotation and the period of rotation around itself are the same. This is the reason why we constantly see the same side.
The duration of the day on the Moon is approximately 13.5 Earth days. Its surface is composed of regolith and basalt and has no atmosphere which exposes it to the cold of space and the solar radiation. Temperatures grow from -153 °C at night to 123 ° C at day respectively.
Its core is a fairly small, solid iron core with a small fluid casing, which is surrounded by a cold mantle that ends up on its surface. The Moon, after its creation, began to gradually cool down. When it was still young, it was hit by a large asteroid in its southern hemisphere whose fragments broke the bark, flooding the surface with lava, where it had craters. When this lava cooled, it created the seas on which new smaller asteroids fell.
Its core is a fairly small, solid iron core with a small fluid casing, which is surrounded by a cold mantle that ends up on its surface. The Moon, after its creation, began to gradually cool down. When it was still young, it was hit by a large asteroid in its southern hemisphere whose fragments broke the bark flooding the surface with lava, where it had craters. When this lava cooled, it created the seas on which new smaller asteroids fell. Its surface is composed of regolith and basalt and has no atmosphere which exposes it to the cold of space and the sun's radiation. Temperatures grow from -153 °C at night to 123 ° C at day respectively.