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 order according to their 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 based on their distance from the Sun. For a better understanding, you can consult the characteristics of the planets of the Solar System, which include both rocky and gaseous minerals.
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 rocky planets. This 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: they are mostly formed by silicates, which you can learn more about in what the planets are made of.
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, gaseous and rocky planets. The main way to differentiate one from the other is that rocky planets generally have a mostly solid surface. This is quite the opposite of gaseous planets, as most of these have a gaseous or even liquid surface. For more information, you can visit our article on the classification of the planets, where we discuss more about its features.
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 core, which is mostly iron. They also have a series of silicate layers surrounding the core, characteristics described elsewhere in our articles.
The Rocky Planets have something especially in common and that is that each of them has a compact rocky surface, like Earth's, and for this reason, it is also said that these planets have a terrestrial surface. The Solar System has eight confirmed planets, but only four have these characteristics. Specifically, Venus, Earth, and Mars have more or less significant atmospheres, while Mercury has almost no atmosphere at all, which you can compare with the characteristics of planet Earth.
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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, which is discussed in our articles on planetary movements. Although some are still active and have erased the features of their original surface.
The 4 rocky planets of the solar system
One: Mercury
El Planet Mercury It has the closest orbit to the Sun. In addition to this, it is the smallest planet in the Solar System, so logically it 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 like from Mercury. You can learn more about this planet in our article on the planets of the Solar System.
The most important thing to imagine is the rocky surface of this planet. If we stood on that ground and looked up at the sky, everything would be different from what we see from our planet. First of all, the Sun would appear two and a half times larger to us, due to the proximity of that planet to the star. In addition, ironically, although the Sun 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 VenusA rocky planet, it is the most similar to planet Earth, based on its characteristics, due to its size, mass, density, and volume. Perhaps this similarity is due to the fact that both planets formed during the same era, from the same nebula. On the other hand, they also have some important differences. You can learn more about the planets in our article on , which compares the characteristics of several of them.
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. For more information about the components of Venus, you can consult .
Three: Earth
Our planet Earth it is the third closest to the sun And it's the only inhabited planet, according to what has been investigated in the explored Universe. Its specific location is the ecosphere, a space surrounding the Sun that has the right conditions for life to exist, due to the combined components it contains. You can read more about the , where the factors that allow life are explained.
It is noteworthy that this planet is the largest of the Rocky Planets. What makes it capable of retaining a gas layer, the atmosphereThe atmosphere, in addition to filtering the sun's rays and preventing the surface from getting too hot during the day or too cold at night, scatters light and absorbs heat. This is detailed in our articles on Earth's crust.
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OAnother characteristic of our planet Earth is that seven out of every ten parts of its surface are water coversAnd in reality, it's the seas and oceans that also help regulate ambient temperature. This is done through a process called the water cycle, where water evaporates and then forms clouds and falls as rain or snow, forming rivers and lakes. For more information on the origin of water, you can consult this article, which details how water is formed on the planet.
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 hues. The Romans identified its hues as blood, and so they also decided to use the name of a god, in this case, the god of war. This planet's atmosphere is very thin and composed primarily of carbon dioxide, which freezes alternately at each of the poles. To learn more about the planets in our Solar System, visit .
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 from the surface, where furrows, islands, and coasts can be seen, which coincides with what we have discussed about curiosities of the solar system.
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.
