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Introduction: The Solar System and its Diverse Planetary Layers

Class 7
Jun 12, 2023

The Size of Object Layers


Our planet Earth is a part of the solar system, which has 8 planets in total revolving around a star named the Sun. All the planets of the solar system have different compositions and are made up of different components. In this session, we are going to look at the different layers of all these planets in detail, one by one.


Every planet has got various layers of certain sizes. For example, the crust, mantle, and core. The following shows the various layers of the planets one by one.

Layers of Mercury:

Mercury is the closest planet to the Sun, and it moves around the Sun in a highly elliptical orbit. It contains about 30% silicate materials and 70% metals. It has no atmosphere because it is small in size and hence, does not have enough gravity to hold onto an atmosphere. It is closest to the Sun, so any atmosphere that it might have gets blasted away due to the solar wind.


The radius of its core is about 1800 km. It has a very high iron content and makes up about 42% of the whole planet. It has molten iron layers surrounding a solid center, which may account for its magnetic field. The mantle is made of silicate materials and is about 600 km thick. The crust of the planet is about 100 to 300 km thick. It solidified before the core did; hence it has ridges and wrinkles.


Layers of mercury

Layers of Venus:

Venus is similar to the Earth in size, mass composition, and distance from the Sun. However, it has no oceans and is fully covered with thick clouds. It has an atmosphere mostly comprised of CO2, a greenhouse gas, that acts as a blanket to keep the heat in. It absorbs the infrared radiation emitted from the surface. That’s why its temperature is the highest among others, i.e., 4710C.

The thick clouds reflect so much sunlight that, whenever visible, Venus is the brightest object in the sky. Its core is probably molten metal, approximately 3000 km thick. Its mantle is rocky and quite similar to that of the Earth’s mantle, approximately 3000 km thick. Its crust is thin, i.e., 50 km thick, and mainly composed of silica rocks.




layers of venus

Layers of Earth:

The Earth is the only planet that is believed to have life on it. The Earth’s atmosphere consists mostly of nitrogen (78%) and oxygen (21%), which affects its climate and weather. It acts as a shield for all the harmful radiation coming from the Sun and also meteors, most of which burn up before striking the surface. It also has an ozone layer in its atmosphere, which protects the life in it from the harmful UV radiation coming from the Sun. It also traps heat.

Inner core: At a depth of 6,360 km below the surface, it is solid and made of iron and nickel.

Outer core: The liquid outer core is 5,150 km below and is made of molten iron and nickel. This is responsible for the Earth’s magnetic field.

Mantle: This thickest layer comprises silicate rocks that are warm and soft. It extends to a depth of 2,890 km.

Upper mantle: At 660 km thick, the upper mantle is brittle and home to seismic activity.

Crust: The crust ranges from 5 to 70 km thick depending on its location.

GlobemantleLayers of earth

Layers of Mars:

The atmosphere of Mars is composed of carbon dioxide, nitrogen, and argon. It is so thin that the average atmospheric pressure is less than 1% of that of the Earth. Mars is too cold, and its atmosphere is too thin to allow liquid water to exist at the surface for long. More water exists frozen in the polar ice caps, and enough water exists to form ice clouds.

Crust: Mars’s crust (25 to 80 km thick) appears to be thicker than that of Earth’s, especially in areas of prior volcanic activity. The high concentrations of iron and oxygen result in rust–iron oxide, which is responsible in part for the red appearance of Mars.

Mantle: Mars has a silicate mantle (1300 to 1800 km thick) that once had volcanic and tectonic activity, which helped shape the planet.

Core: The core is mostly solid (3000-4000 km diameter), containing iron and nickel as well as sulfur. It does not generate a magnetic field, as it is in a solid form.

Layers of Mars


Layers of Jupiter:

Since Jupiter is a gaseous planet, it’s mostly about the atmosphere. The gases get denser, hotter, and under greater pressure as we go further toward the center. Jupiter is about 75 percent hydrogen and 24 percent helium. There are also traces of ammonia, methane, carbon, hydrogen sulfide, and other elements and compounds.

Current projections for the interior show a layer of liquid metallic hydrogen along with helium surrounding the core, with a layer of molecular hydrogen outside. There is no actual boundary between the liquid and gaseous layers. The temperature at the cloud layers is around -1450 C, and at the core, it increases heavily to 97000 C.

Core: Its rocky core is believed to be 10 to 15 Earth masses, super-hot, and highly pressurized.

Liquid hydrogen: Temperatures are hot enough to turn the hydrogen here into a metallic liquid, also the source of Jupiter’s magnetic field.

Transitional zone: The liquid metallic hydrogen transitions as temperatures and pressures drop closer to the surface.

Molecular hydrogen: Plain hydrogen with a little helium change from a liquid in the underlayer to gas at the surface.

Layers of Jupiter

Layers of Saturn:

Saturn is one of the gas giants as it has no solid surface and it’s mostly composed of gases. However, it has a rocky core, which is similar in composition to the Earth’s core, which comprises of iron, nickel, and silicate rock. It is estimated to be around 10 and 20 times the size of the Earth’s core. The cloud cover is mostly colored yellow by ammonia, and there’s a mild weather system.

Density, pressure, and temperature all increase as we pass through the atmosphere and into the core, resulting in a very hot interior at about 11,700 degrees Celsius. Saturn has a magnetic field 578 times stronger than Earth’s. Scientists believe that the metallic hydrogen layer generates an electric current that is responsible for the magnetic field.

Rocky core: The core is likely primarily iron and, although small, very dense.

Ice: This isn’t water ice as we know it, but a mixture of ammonia, methane, hydrogen, and water.

Liquid metallic hydrogen: The hydrogen at this depth is under such high pressure that it transforms into a metallic state.

Molecular hydrogen: This layer of hydrogen is liquid that transitions to gas as you get closer to the atmosphere.


Layers of Uranus:

The term ‘gas giant’, used for Uranus, implies that it is solely composed of gases, but studies indicate that it actually has a core of silicate rock encased in ice and topped with a gaseous layer. Uranus is also much cooler inside than the other gas giants – it’s actually the coldest planet in the Solar System.

The atmosphere of Uranus is composed of hydrogen and helium, with a liquid core composed of water, methane, and ammonia. The blue-green color of Uranus is due to the way that methane in its atmosphere absorbs visible and near-infrared light.

Core: Uranus is believed to have a small core comprising silicate rock, iron, and nickel.

Mantle: Uranus’s mantle is icy but fluid and includes water, methane, and ammonium.

Atmosphere: The outer gaseous layer of Uranus is mostly hydrogen and helium.

Clouds: Uranus has multiple cloud layers that include water, ammonium hydrosulfide, ammonia, hydrogen sulfide, and methane.

Layers of Uranus

Layers of Neptune:

Neptune is called a gas giant. However, it is not solely composed of gases. Its core contains iron, nickel, and silicate rock, which is somewhat larger than planet Earth. Its atmosphere, which surrounds the mantle is about 80 percent hydrogen, 19 percent helium, and traces of ammonia, water, and methane.

The presence of methane gives Neptune its bright blue color. It is different from Uranus as it has massive winds and storms going on continuously. Most of these winds blow in a direction opposite to that of the planet’s rotation.

Core: Neptune has a small rocky core of iron, nickel, and silicates.

Mantle: The icy fluid mantle comprises ammonia, water, and methane.

Atmosphere: The layered atmosphere of Neptune is mostly hydrogen and with different cloud compositions depending on their elevation.

Layers of Neptune

Size of Object Layers


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