When we talk about the whole set of solar system we have to refer not only to the planets but to the natural satellites. A natural satellite is a non-artificial celestial body that orbits another. Satellites are normally smaller in size than the body it is continually circling. This movement is due to the attraction exerted by the force of gravity of the larger body on the smaller one. It is the reason why they begin to orbit continuously. The same is true of the orbit of the earth with respect to the sun.
In this article we are going to tell you all the characteristics and curiosities of natural satellites.
Natural satellites in the solar system
When we talk about a natural satellite too it is usually referred to by the common name of moons. Since we call our satellite the moon, other satellites of other planets are referred to by the same name. For example, it is often said "the moons of Jupiter«. Every time we use the term moon, it refers to the celestial body that moves around another body in the solar system, although it can do so around the dwarf planets as well as the inner planets, Outer planets and even other smaller bodies such as asteroids.
The solar system is made up of 8 planets, 5 Tiny planets, comets, asteroids and at least approximately 146 natural satellites of planets. The best known of all is ours known as the moon. It is the only satellite of planet Earth. If we compare the number of satellites between the inner and outer planets, we see a significant difference. The inner planets have very few or no satellites. On the other hand, the rest of the planets, known as the outer planets, have several satellites due to their large size.
As all these natural satellites were discovered little by little, they were given various names. Most of these names come from Greek and Roman mythology. For example, one of Jupiter's moons is known as Callisto. If you want to learn more about the moons of this gas giant, you can read our article on Jupiter satellites and its fascinating formation.
Key features
Let's analyze the characteristics of these celestial bodies. First of all, it must be a solid celestial body. There are no natural satellites composed of gases, as are the gas giants. All natural satellites are made of solid rock. They typically lack an atmosphere of their own. Being so small, these bodies do not harbor an atmosphere of their own. Having an atmosphere would cause various changes in the dynamics of the solar system.
We know they exist about 146 natural satellites in total in the solar system. The question scientists often ask is how the planets they orbit maintain their orbits and don't get too far away or too close. This is where we refer to what we mentioned earlier. This is due to gravitational attraction. As the early planets began to grow and develop, they acquired a gravitational field capable of keeping other bodies close to them. Gravity doesn't cause a celestial body to approach another, but rather causes it to orbit around it.
This is the same thing that happens with our planet around the sun. A celestial body moves around another larger body at a constant speed. The formation of a natural satellite is due to different processes taking place in the solar system. Some of these formed from clouds of gas and dust that were found around the planets during the early years of their formation. The fact that they were close to the planet caused gravity to pull the particles together to form a satellite. If you want to better understand what a satellite is in general, check out our article on... what is a satellite and the differences with artificial satellites.
They are not all the same size. We find some that are larger than the moon and others much smaller. The largest moon measures 5.262 kilometers in diameter and is called Ganymede belonging to Jupiter. As expected, the largest planet in the solar system must also host the largest satellite. If we analyze the orbits, we see that they are either regular or irregular. Not all are fixed. The same applies to morphology. Some bodies are spherical, while others have a rather irregular shape. This is due to the process of their formation. It is also due to the speed of their formation. Those bodies that formed quickly acquired a more irregular shape than those that formed more slowly.
The same applies to orbit and time period. The Moon, for example, takes approximately 27 days to orbit the Earth. In its counterpart, Ganymede completes its orbit in 7.16 days, despite the fact that the planet Jupiter is much larger than Earth.
Types of natural satellites
According to the orbits that each one has, there are several types of satellites:
- Regular natural satellites: These are bodies that revolve around a larger body in the same direction as the body revolves around the sun. That is, the orbits have the same direction even if one is much larger than the other. For example, the moon rotates from east to west, and its planet does the same. Therefore, it is a regular satellite since it is in direct orbit around the larger body. If you want to know more about the Astro orbiting in space, see our related article.
- Irregular natural satellites: Here we see that their orbits are very distant from their planets. This may be explained by the fact that they did not form near the planets themselves. Rather, these satellites may have been "captured" by the gravitational pull of the planet in question. There may also be an origin that explains the remoteness of these planets. This could be that they were once comets that entered near the orbit of a giant planet. These irregular satellites have highly elliptical and inclined orbits.
I hope that with this information you can learn more about natural satellites and their main characteristics.