The rocky planets they are one of the two types of planets that exist in our Solar System. And although there are multiple ways to classify the planets, it is according to their composition that they have two types specifically: the gaseous planets and the rocky ones. In this article we are going to detail everything about the rocky planets that are within our Solar System.
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There are four rocky planets that revolve around the Sun and they are also named terrestrial planets or telluric planets of the Solar System, which are: Mercury, Venus, Earth and Mars, respectively in the order according to the proximity to the Sun. In addition to this, they are also called inner planets. And the reason for this is that the classification of inner and outer planets is done based on the distance from the Sun.
It is quite curious to note that in the Solar System there is a dividing line and it is the asteroid belt, which divides the gaseous and tocos planets. It is located between the planets Mars and Jupiter. However, it is essential to verify what makes a planet have a rocky composition and the answer is that they have a main characteristic as they are formed mostly by silicates.
These so-called silicates are the most abundant group of minerals there is. In addition to this, they are also the most geologically important group of minerals, since they are petrogenic, which means they are the minerals that make up rocks. However, it is noteworthy that minerals and rocks are not exactly the same.
General characteristics of rocky planets
As has been mentioned, according to its composition there are two types of planets in the Solar System. That is to say the gaseous and the rocky ones. The main way to differentiate one from the other is that the rocky ones have the general characteristic of having a mostly solid surface. Quite the opposite of the gaseous planets, since these mostly have a gaseous or even liquid surface.
The only planet that is among the Rocky Planets and that has a part of its liquid surface, is the planet Earth. On the other hand, it is important to note that the Rocky Planets share in common, a subsurface structure. This means that they all have a metallic corewhich is mostly iron. They also have a series of silicate layers that surround the core.
The Rocky Planets have something especially in common and that is that each of them has a compact rocky surface, like that of the Earth and for this reason these planets are also said to have a terrestrial surface. The Solar System has eight confirmed planets, but there are four that have these characteristics. Specifically Venus, Earth and Mars have more or less significant atmospheres, while Mercury has almost no atmosphere at all.
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These planets have a very high selection of matter. This is what gives rise to products such as uranium, thorium and potassium. They also have unstable nuclei that accompany radioactive fission phenomena. Precisely these elements are the ones that have developed enough heat to generate volcanism and important tectonic processes. Although some are still active and have erased their original surface features.
The 4 rocky planets of the solar system
One: Mercury
El Planet Mercury it is the one with the closest orbit to the Sun. In addition to this, it is the smallest planet in the Solar System, so it logically turns out to be smaller than Earth. However, it is larger in size than our satellite, the Moon. Being on Earth we cannot understand what it would be like to live on that planet. However, scientists have taken it upon themselves to help us visualize what our panorama would be from Mercury.
The most important thing to imagine is the rocky surface of this planet, when we stand on that ground and look at the sky, everything would be different from what we see from our planet. In the first place, the Sun would seem two and a half times larger to us, due to the proximity between that planet and the star. On top of that, ironically, even though Sol is closer to Mercury, the sky would always be black and the reason for this is because it does not have an atmosphere that can scatter light, as it does on Earth.
A curious fact is that this rocky planet is holder of the name of Mercury, due to a time where the ideology to the gods abounded. In this sense, this name comes from a supposed messenger of the gods and the reason is because the planet moved faster than the other planets. He goes around the Sun in less than three months. Instead, Mercury rotates slowly on its axis, once every 58 XNUMX/XNUMX days. Before he did it faster, but the influence of the Sun has been slowing him down.
This inner or terrestrial planet it has no satellites. Having an inner orbit to that of the Earth, it periodically passes in front of the Sun, as does Venus. This phenomenon is called an astronomical transit. This planet has an equatorial radius of 2.440 km, unlike the equatorial radius of the Earth which is 6.378 km. On the other hand, the time in which it orbits around the Sun is 87,97; as opposed to the 365,256 days it takes for the Earth to revolve around the Sun.
Two: Venus
The second planet that belongs to the Solar System is the planet Venus. A rocky planet, which according to its characteristics is the most similar to planet Earth, due to its size, mass, density and volume. Perhaps this resemblance is due to the fact that both planets were formed during the same time, from the same nebula. On the other hand, they also have some important differences.
One of the things that differentiates Venus from Earth is that the first mentioned does not have oceans. In addition to this, it has a dense atmosphere which is what causes a Greenhouse which raises the temperature up to 480 ºC. Previously, the first astronomers had a misconception about Venus as they believed that they were two different bodies, because sometimes it is seen a little before sunrise and, sometimes, just after sunset.
On the other hand, it is noteworthy that Venus spins very slowly, on its own axis. This phenomenon makes the day on Venus last longer than the year. Another curious fact is that when it rotates, it does so in the opposite direction to that of the other planets and for this reason, on that planet the Sun rises in the west and sets in the east, contrary to what happens on our planet Earth.
Compared to planet Earth, Venus has a equatorial radius of 6.052 km, quite similar to that of the Earth, which is 6.378 km. On the other hand, the time it takes to complete its orbit around the Sun is 224,7 days and, as has been said, its average surface temperature is 482º C, while that of the Earth is 15º C.
Three: Earth
Our planet Earth it is the third closest to the sun and it is the only inhabited one, according to what has been investigated in the explored Universe. Its specific location is the ecosphere, it is a space that surrounds the Sun and that has the right conditions for life to exist, due to the united components that it possesses.
It is noteworthy that this planet is the largest of the Rocky Planets. What makes it capable of retaining a gas layer, the atmosphere. The atmosphere, in addition to filtering the sun's rays and preventing the surface from getting too hot during the day or cooling down at night, is what scatters light and absorbs heat.
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OAnother characteristic of our planet Earth is that seven out of every ten parts of its surface are water covers. And in reality, it is the seas and oceans that also help regulate the temperature of the environment. It does this through a process called the water cycle, where the water that evaporates then forms clouds and falls as rain or snow, forming rivers and lakes.
On the other hand, this rocky planet also has quite peculiar poles, which, receiving little solar energy, cause the water to turn into ice and form the polar ice caps. The South Pole is larger and concentrates the largest reserve of fresh water.
Four: Mars
The fourth rocky planet is also the fourth planet in the Solar System in terms of its location due to its distance from the Sun. This planet is also known as the Red planet for its pink tones. The Romans identified their shades as blood and for this reason they also decided to use the name of a god and in this case, the god of war. The atmosphere of this planet is very thin and consists mainly of carbon dioxide, which alternately freezes at each of the poles.
Mars It is a rocky planet that also has water, but only 0,03%, which is a thousand times less than the amount on Earth. Studies show that Mars had a more compact atmosphere, with clouds and precipitation that formed rivers. And this conclusion is deduced by the surface, where furrows, islands and coasts can be guessed.
Mars has large temperature differences which is what causes very strong winds. In addition to this, soil erosion helps form dust and sand storms that further degrade the planet's surface. Something that should be noted is that before the respective space explorations were carried out, it was thought that there could be life on Mars. However, observations have failed to show if it does, although it might have in the past.
Planet Earth so far turns out to be the planet with the right components to form particles with life. It has only been estimated that life could exist on Mars, however not only the Rocky Planets give that possibility, we have to wait if there is life among the gaseous planets or in one of their satellites. For now, we still get the greatest mystery of Universe.