Solar System Planets Composition and Earth's Interior Structure

Planets: Composition and Atmospheres

Mercury

Mercury's magnetic field has a very low intensity. It has no real atmosphere, with only traces of sodium and potassium.

Venus

Venus: The atmosphere is made up of CO2. On its surface, temperatures are around 500 °C. It has dynamic geological similarities to those of Earth.

Earth

Earth: The atmosphere has a considerable proportion of oxygen. Its position in the solar system makes this the ideal conditions for the development of life.

Mars

Mars: The atmosphere, very dynamic, is composed of 95% CO2, and 5% for nitrogen and helium. It has water (ice) in its polar caps.

Jupiter

Jupiter is a gaseous planet (81% hydrogen and 18% helium) with a small solid core. It has 16 satellites.

Saturn

Saturn: The atmosphere is hydrogen and helium but in lower proportion than in Jupiter. The most notable feature is the thousands of rings, which are formed by particles of helium. It has 17 satellites.

Uranus

Uranus: It is believed that it consists of three shells: the rocky core, a water mantle, and an atmosphere (hydrogen, helium, ammonia and methane).

Neptune

Neptune is a planet similar to Jupiter; its atmosphere consists of hydrogen and helium. It has 4 rings, with particles similar to those of Saturn. It has 8 satellites.

Seismic Waves and Earth's Internal Structure

P Waves (primary or compression)

P waves, primary or compression: compress and expand the material that they cross in the same direction of propagation. They move at an average speed of 5.5 to 13.5 km/s.

S Waves (secondary or shear)

S waves, secondary or shear: deform the material particles that they pass through, so that they oscillate in a direction perpendicular to the propagation. Their speed is about 4 to 8 km/s.

Surface Waves

Surface waves: They are slower. They form when the other seismic waves reach the surface and are transmitted exclusively by it, causing damage.

Inner Core

Inner Core: Believed to have solidified due to the pressure inside the planet.

Outer Core

Outer Core: It behaves like a liquid and moves by convection. It creates a dynamo that generates Earth's magnetic field.

Gutenberg Discontinuity

Gutenberg discontinuity: Located at 2,900 km depth. S waves do not pass through here, so it is believed to mark the top of the liquid outer core.

Upper Mantle

Upper Mantle: Located between 10 and 400 km depth. It is believed that this consists of minerals rich in iron and magnesium.

Mohorovičić Discontinuity

Mohorovičić discontinuity: Located about 10 km under the ocean floor and 30–40 km under the continents. It signals a change in the composition of the rocks and is the boundary between the crust and mantle.

Oceanic and Continental Crust

Oceanic Crust. Continental crust.