The stellar system of the Milky Way galaxy in which we live includes the Sun and 8 more planets orbiting around it. Scientists are primarily interested in studying the planets closest to Earth. However, the satellites of the planets are also very interesting. What is a satellite? What are their types? Why are they so interesting for science?
What is a satellite?
A satellite is a small body that rotates around the planet under the influence of gravity. Currently, we know 44 such celestial bodies.
Satellites are absent only in the first two planets of our stellar system, Venus and Mercury. Earth has one satellite (Moon). The "Red Planet" (Mars) has 2 celestial bodies accompanying it - Deimos and Phobos. The largest planet of our star system - Jupiter - has 16 satellites. Saturn has 17, Uranus has 5, and Neptune has 2.
Types of satellites
All satellites are divided into 2 types - natural and artificial.
Artificial - celestial bodies created by people, which open the opportunity to observe and explore the planet, as well as other astronomical objects. They are necessary for mapping, weather forecasting, broadcasting signals. The largest man-made "companion" of the Earth is the International Space Station (ISS). Artificial satellites are not only on our planet. Over 10 such celestial bodies revolve around Venus and Mars.
What is a natural satellite? They are created by nature itself. Their origin has always aroused genuine interest of scientists. There are several theories, but dwell on the official versions.
Near each planet there is an accumulation of cosmic dust and gases. The planet attracts celestial bodies that fly close to it. As a result of this interaction, satellites are formed. There is also a theory according to which fragments are separated from cosmic bodies colliding with the planet, which subsequently acquire a spherical shape. According to this assumption, the natural satellite of the Earth is a fragment of our planet. This is confirmed by the similarity of terrestrial and lunar chemical compositions.
Satellite orbits
There are 3 types of orbits.
The polar is tilted to the equatorial plane of the planet at a right angle.
The trajectory of the inclined orbit is shifted with respect to the equatorial plane by an angle less than 90 0 .
Equatorial (also called geostationary) is located in the plane of the same name, along its trajectory the celestial body moves with the velocity of the planet around its axis.
Also, the satellite orbits in their form are divided into two basic types - circular and elliptical. In a circular orbit, a celestial body moves in one of the planes of the planet with a constant distance above the surface of the planet. If the satellite moves in an elliptical orbit, this distance changes within the period of one revolution.
Natural satellites of the planets of the solar system: interesting facts
Saturn’s satellite Titan has its own dense atmosphere. On its surface there are lakes, which include liquid hydrocarbon compounds.
Europe (the satellite of Jupiter) is covered with ice, under which the ocean is supposedly located. Scientists have also hypothesized that within this ocean there are active geothermal sources.
Another satellite of Jupiter - Io - caused particular interest of astrophysicists. Active volcanoes were discovered on it.
Artificial Earth Satellites (AES)
According to the generally accepted definition, an artificial satellite is called an aircraft that at least once made a revolution around the Earth. The first artificial satellites were put into low Earth orbit by the Soviet Union (1957) and the United States (1958). Due to this, the density of the upper atmosphere was measured, and the propagation of radio signals was studied. This was a real breakthrough in space exploration and the beginning of the Space Age.
Following the USSR and the United States, satellites were launched by France (1965), Australia (1967), Japan (1970), China (1970) and Great Britain (1971).
Space research is based on international scientific and technical cooperation. So, for example, USSR-friendly countries launched satellites from Soviet cosmodromes. Some satellites manufactured in Canada, France, Italy, since 1962 were launched using rocket launchers developed by the United States.
What is a satellite? This is a cosmic body rotating in orbit around a planet. By origin they are natural and artificial. The world community is particularly interested in the natural satellites of the planets, because they still have many mysteries in themselves, and most of them are still waiting for discovery. There are projects on their study of private, state and world significance. Artificial satellites make it possible to solve applied and scientific problems both on the scale of an individual planet and of the entire outer space.