When we talk about the entire solar system, we must refer not only to the planets but also to natural satellites . A natural satellite is a non-artificial celestial body that orbits another. Satellites are usually smaller than the body they constantly orbit. This movement is due to the gravitational pull of the larger body on the smaller one. This is why they begin to orbit continuously. The same occurs with Earth's orbit around 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, it's often referred to by the common name "moon." Since we call our own satellite "the moon," the same name is used for the satellites of other planets. For example, we often say "the moons of Jupiter ." Whenever we use the term "moon," it refers to a celestial body that orbits another body in the solar system, whether it's dwarf planets, inner planets , outer planets , or even smaller bodies like asteroids.
The solar system consists of eight planets, five dwarf planets , comets, asteroids, and at least 146 natural satellites. The most well-known of these is our own, the Moon. It is Earth's only natural satellite. 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 outer planets have several satellites due to their large size.
As these natural satellites were discovered gradually, 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 consult our article on Jupiter's satellites and their fascinating formation.
Key features
Let's analyze the characteristics of these celestial bodies. First of all, they must be solid bodies. There are no natural satellites composed of gases, as is the case with gas giants. All natural satellites are made of solid rock. Most likely, they don't have their own atmosphere. Because they are so small, these bodies don't have their own atmosphere. Having an atmosphere would cause various changes in the dynamics of the solar system.
We know that there are approximately 146 natural satellites in the solar system. Scientists often ask how they maintain their orbits and don't drift too far away from or too close to the planets they orbit. This is where we refer to what was 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 one celestial body to move closer to another; rather, it causes it to orbit around it.
This is the same thing that happens with our planet around the sun. One celestial body moves around another, larger body, and both do so at a constant speed. The formation of a natural satellite is due to various processes that take 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. Their proximity to the planet caused gravity to pull the particles together, eventually forming a satellite. If you want to better understand what a satellite is in general, see our article on what a satellite is and the differences between natural and artificial satellites.
Not all moons are the same size. Some are larger than the moon, while others are much smaller. The largest moon, Ganymede, is 5.262 kilometers in diameter and belongs to Jupiter. As expected, the largest planet in the solar system also has the largest satellite. Analyzing their orbits, we see that they are either regular or irregular. Not all are fixed. The same is true for their morphology. Some bodies are spherical, while others have a rather irregular shape. This is due to their formation process and the speed of that formation. Bodies that formed quickly acquired a more irregular shape than those that formed more slowly.
The same applies to orbit and orbital period. The moon, for example, takes approximately 27 days to orbit the Earth. Ganymede, on the other hand, completes its orbit in 7.16 days, even though 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.