We explain what natural satellites are, their types and characteristics. The Moon and other natural satellites of the Solar System.
What are natural satellites?
a natural satellite It is a celestial body that orbits another larger body and that accompanies it in the translation movement. The natural satellites that orbit the planets are called “moons” (some planets have several moons in their orbit). The only ones that do not have natural satellites are Mercury and Venus.
Many scientists maintain that planets and other large bodies may have acquired their natural satellites by capturing them by gravitational attraction. That is, some moons used to move through space independently and, when they passed close to a body of greater density and size, they began to form part of its orbit.
In other cases, such as that of The Earth's Moon was created from a large impact between an asteroid and planet Earth. Rocks and dust resulting from the explosion of the crash spread into space and then clumped together to form the Moon, located close enough to Earth to be trapped in its orbit.
Characteristics of natural satellites
Natural satellites can vary in terms of composition, size, shape, etc. However, they have certain characteristics in common:
- move in the orbit of a larger celestial body due to the force of gravity coming from it.
- are usually solid bodies and generally do not have a noticeable atmosphere.
- Their orbits can be regular or irregular.
- Their gravitational force affects the planet they orbit (In the case of the Earth, the Moon's gravity causes the tides to rise).
Both planets and natural satellites have their own force of gravity. Although the power of the planets is greater (which keeps the satellite in its orbit), the satellite also exerts some influence on the planet.
Types of natural satellites
Natural satellites are classified into:
- Shepherd satellites Those that are located in the rings of a planet, especially the “giant” or “outer” planets of the Solar System.
- Coorbital satellites Those that make up two or more satellites in the same orbit of a planet.
- Asteroid satellites Those, generally small, that revolve around asteroids.
Natural satellites are also classified by their type of orbit, which can be:
- Regular Those satellites that maintain a constant orbit around another celestial body, that is, in the same direction as the planet.
- Irregular Those that maintain orbits very far from the planet they orbit and that are usually elliptical and inclined.
Natural satellites in the Solar System
In the Solar System there are around 160 confirmed natural satellites and another hundred still under study.
The first to detect that other planets also had moons was Galileo Galilei, who in 1610 was able to recognize the four largest moons of Jupiter, a planet that has the largest number of natural satellites (at least 69, detected so far). In second place is Saturn with 61 confirmed moons.
Planets, asteroids and comets orbiting different stars, Like the Sun, they can also be considered natural satellites.
The Solar System has eight confirmed planets and millions of minor planets, asteroids, comets and other celestial bodies that orbit the luminous star. All of them can be considered, in some way, natural satellites.
The Moon
The Moon is the only natural satellite of the Earth has a diameter of 3,476 kilometers (a quarter of that of the Earth) and is the fifth largest satellite in the Solar System. It moves at a speed of 3,700 km per hour and takes 27.3 days to orbit the planet, a period called “orbital” or “sidereal” which means “of the stars” or “related to the stars.”
However, the time between one full moon and the next is 29.5 days. That extra time is due to the change in angle as the Earth rotates around the Sun.
The Moon has its own force of gravity. Although it is much smaller than the gravitational pull of the Earth, exerts influence on the planet since it causes the tides to rise that is, the liquid terrestrial masses are attracted by the gravitational force of the Moon.
The rise of the tide does not always occur at the same time each day, but varies with the lunar phases that appear at different times. Depending on the instance of the lunar phase, the intensity of the tide varies, for example:
- Neap tides They occur during the waxing and waning lunar phases, and are characterized by small or slight changes in the seas.
- Spring tides They occur during the phases of the full and new moon, when the satellite aligns with the Sun and the Earth, which causes the high tides to be even greater, because the gravitational attractions of the luminous star and the planet are added.
Artificial satellites
artificial satellites are highly complex machines created by humans and launched into space through rockets so that they orbit around a certain celestial body, for example, the Earth. Its objective is to collect data, tests and other information to prepare maps and to study different parts of the body's surface.
In the late 1950s, the former Soviet Union launched the world's first artificial satellite which was the size of a basketball and managed to transmit a simple Morse code signal.
Currently, artificial satellites are capable of receiving and retransmitting thousands of signals simultaneously ranging from digital data to the programming of television systems.
Continue in: Artificial satellites
References
- “What is a satellite?” at NASA.
- «Natural satellites» in Science learn.
- «Natural satellite lesson for kids» in Study.
- “What is a satellite?” in OSR.
