The mentioned earlier, there is the risk

 The Sun  The Sun is the central star in the Solar system. The existence of life on Earth depends upon the activity of the Sun. It consists of  hot ionized plasma, that cant be found in the normal conditions on our planet. Plasma features unique characteristics and the temperature of the star rises every year. Some scientists claim that in future the Sun will explode and it will be the end of the Solar System. The size of the Sun is enormous compared to the planets of the Solar System. In fact, it features approximately 99.8 percent of its overall mass and it is almost 330, 000 times heavier than our planet. At the same time, its not that big, comparing to the giant stars that can be found outside the Solar System. The Sun is often called the yellow dwarf, which is the common definition of  G-type stars. Although this term is not 100 percent accurate, because not all stars of this type have the yellow color. Yellow Stars are simply brighter than others, but there are numerous white, red, and orange dwarfs. The Sun is middle aged. The scientist claim that its state will remain stable in the nearest five million years. However, as it was mentioned earlier, there is the risk of explosion and destruction of the Sun. In the end of this process the Sun might turn to the red giant.                  The Sun represents/ is seen different in the cultures of different nations. People considered the Sun to be their main god from the ancient times. In fact, the eldest pagan traditions were based on the worship of this star. Mercury  Mercury was named after the Antique god of eloquence and commerce. It is the closest planet to the Sun in the Solar System and as the result, it has the shortest orbital period. This is called the inferior planets, which means that the orbit of Mercury is inside the orbit of Earth that moves around the star.  Mercury is visible in the sky only in the early morning and in the evening. It is possible to  see all phases of the planet from earth, because Mercury’s orbit corresponds to the orbit of the Earth. Mercury goes through its full cycle of its phases in 116 days  One of the most fascinating things about Mercury is its rotation. It is characterized by the captured rotation around the Sun, which is also called  tidal locking. Mercury’s spins around orbit are synchronized with the planet’s rotation around the Sun. When Mercury does three spins around its own axis, it turns two times around the Sun. Thus, two years on Mercury are marked with the only rotation around the fixed star.  There are no natural satellites on Mercury. Humanity has visited this planet twice in its history. The first spaceship Mariner 10 reached Mercury in 1974 and in 1975. The second expedition was in 2004 by MESSENGER  MESSENGER could not launch on the planet for four years. It crashed into Mercury in 2015 when it ran out of fuel. Before that, the robotic spacecraft of NASA orbited the planet more than 4 thousand times. Something very interesting is that MESSENGER discovered ice on the north pole of Mercury. MESSENGER is the name of the separate space program of NASA all about  Mercury. It is the backronym than is deciphered as Mercury Surface, Space Environment, Geochemistry, and Ranging. This program aims at researching the magnetic field of the planet, its geology and chemical composition.Venus  The second closest planet from the Sun is Venus. Its rotation period around the Sun is the longest one in the Solar System. Something unique about Venus is that its direction of rotation is the opposite to the other planets. Venus does not have natural satellites, just like Mercury..  The name of the planet is also connected with the Antique culture. It is named after the goddess of beauty and love, and it is considered to be the planet of the femininity. Venus can be seen from Earth and it is a very bright planet. It is possible to see it during the day with the naked eye.  An interesting fact about Venus is that it is very similar to Earth in certain areas. For example, both planets have the common bulk, their proximity to the Sun is close to equal, and they have the same size. At the same time, the atmosphere of Venus is not suitable for living, because it consists mainly of carbon dioxide and it is very dense. The pressure of the atmosphere is also high. It is impossible to see the surface of Venus from space in the light from the Sun. The planet is covered with the clouds that consist of sulfuric acid. These clouds serve as the mirror that reflects the visible light. Researchers assume, that there might have been oceans on Venus. Though, they evaporated with the time because of  the greenhouse effect. This planet is an evident example of the possible outcome of Earth. The planet has a weak magnetic field. The water on Venus was primarily destroyed by the  radiation of light, and then the hydrogen that was left after. Now, Venus is absolutely dry and its surface is like a desert.Earth  Our planet is considered to be the only place in the Solar System and in the entire Universe with life. The planet has one natural satellite called the Moon, and it is possible to see it in the sky with the plain eye. The gravity of Earth interacts with it and the Moon influences tides on the planet.  It also interacts with the Sun. The period during which Earth makes the full circle around the Sun is called the year. The planet also spins around its own axis. It leads to the change of the seasons on Earth (Chown 72).  Earth is the terrestrial planet and it is the largest from them. The other terrestrial planets are Mars, Venus, and Mercury. In fact, this notion refers to the planets that have the similar composition as Earth and that are potentially suitable for life. This theme is actively developed by the science fiction and the official science also shares these ideas, which explains the interest in researching them.  The biggest part of Earth is covered by oceans, which is considered to be one of the reasons that determine the possibility of life on the planet. Hydrosphere covers more than 71 percent of the surface of the planet. The poles of Earth are covered with ice. The rest of the surface consists of islands and continents  (Chown 74-75). As the result, the density of the population on these territories is very high and people struggle for the territory. More than 7.6 billions of people live on the planet. Their lives depend on the normal functioning of the biosphere, atmosphere, and the amount of natural resources. Though, the humanity does not think much about preserving Earth and it will use its resources until their end.  The same conclusion can be applied to preserving the biosphere. More than 99 percent of species that used to live on the planet do not exist now or are on the brink of extinction. Even though the destruction of Earth is usually connected with the explosion of the Sun that will become the red giant, the human-made problems connected with ecology might also lead to serious problems in future (Benson, Michalski 68).  Mars  Mars is considered to be the last terrestrial planet in the Solar system. It is named after the god of war from the Roman mythology. The planet is characterized by the red color of its surface, which is the result of the iron oxide that covers the territory of Mars. It is possible to see it in the telescope (Bennett 80).  Mars has the atmosphere that is similar to Earth. It makes the scientists argue whether life is possible on this planet. The atmosphere is rather thin and it allows them to see the craters, deserts, valleys, and the ice caps that remind the researchers of our planet. Mars has two natural satellites, Deimos and Phobos.  Mars is comparatively well-researched and the investigation continues. There are many signs that show that Mars might be potentially habitable. There is the Boreralis basin in the northern part of the planet and it covers approximately 40 percent of the planet’s territory. Valles Marineris is considered to be one of the biggest canyons that be found in the Solar System. All these signs show that the life in the primitive form might exist in the places where there is water (Bennett 83).  The most interesting issue about Mars is the current space program. The missions are planned and are in the process of preparation. For instance, Mars 2020 is the program that is lead by NASA and ExoMars is the program that is lead by Russia and European Union. The robots will research the underground ice on Mars and they will work mainly in the region named the Utopia Planitia (Bennett 84). Jupiter Jupiter is named after the Roman god, just like the other planets of the Solar System. The astronomers of the ancient times knew about its existence, because it can be seen from Earth without strong lenses. It is the largest planet in the Solar System and it is considered to be the gas giant (Benson, Michalski 110).  The planet consists of helium and hydrogen, which is the basis of its mass. There are also rocky elements on Jupiter, but there is no solid ground in the traditional understanding on this planet. The speed of Jupiter’s rotation is very high and it influences the form of the planet, that is the oblate spheroid(Benson, Michalski 111). Gas giants experience anticyclonic storms due to their turbulent atmospheres. Jupiter is not the exception, because it is also classified as the gas giant. For example, the scientists observe the so-called Great Red Spot on Jupiter starting from the beginning of the 19th century. Though, there is still no definitive answer concerning the nature of the red color of this storm (Benson, Michalski 112-113).  The exploration of Jupiter is the interesting theme. The researchers plan to take the probe of ice oceans that cover Europa, Jupiter’s moon. Until this moment, the planet was explored by the robotic spacecrafts in the context of Voyager, Galileo and Pioneer missions. The spacecraft of New Horizon used gravity of Jupiter to change its trajectory to move to Pluto and to increase its speed  (Chown 90). Saturn  Saturn is the second gas giant that goes after Jupiter. Even though it is almost 10 times bigger than Earth, it is 8 times less dense than our planet, which makes it inappropriate for life. The planet is composed mainly of oxygen and silicon components and has the iron-nickel composition (Chown 80).  The outer layer of Saturn is in the form of gas. The planet has a yellow pale color and it is because of presence of crystals of ammonia in its atmosphere. The magnetic field of Saturn is the result of the electrical current that goes within the layer of metallic hydrogen. It is rather weak, comparing to Earth  (Bennett 92).  The peculiar issue about this planet is that the speed of wind is enormous on its surface.  It can reach almost 2 thousand kilometers per hour. The wind speed is higher only on Neptune in the entire Solar System. Though, the most well-known characteristic of Saturn is its system of rings. There are more than 62 moons that rotate on the orbit of the planet. Only 53 of them have names officially. The largest moon of Saturn is Titan and it is the only moon that is characterized by the atmosphere. All moons consist of dust, ice and rocks  (Bennett 82).  Saturn is unique due to the rings that surround the planet. They consist mainly of ice water with small percentage of carbon. The planetary rings are rather thick and are nearly 20 meters. The ideas about the origins of these rings are not unanimous. According to the most popular version, they are the remnants of the material from which the planet itself was formed. According to the second theory, they are the small parts of the destroyed natural satellite of Saturn (Chown 83).  The Cassini-Huygens space mission is the part of the program that focuses on the research of Saturn and its moons and rings. The robotic spacecraft managed to land on Titan, the biggest moon of Saturn and to send the probe of the satellite and the planet itself to Earth. Missions to Saturn require much time due to the distance between Earth and the researched planet  (Bennett 96-97). Uranus  The composition of Uranus is similar to the one of Neptune. Both planets are considered to be ice giants, in the contrary to Saturn and Jupiter, that are gas giants. The planet’s atmosphere  consists primarily of helium and hydrogen. Though, there is also much methane and water in it, which explains the classification of Uranus (Chown 28).  As other gas and ice giants, this planet has the system of rings and a comparatively big number of moons. The peculiar issue about Uranus is that its axis of rotation is not usual, the planet is slightly bent. As the result, the placement of poles is also original. The poles of Uranus are in the place where other planets of the Solar System have equators due to this slant of the axis. Throughout history, Uranus was considered to be the star. Though, it was discovered in the ancient times and that time lenses did not allow the scientists to understand that it was the planet. It was first observed in the 2nd century BC by Hipparchos and then it was included into Almagest, the catalog of starts written by Ptolemy (Chown 29).  The original axis of Uranus results in drastic changes of the weather on the planet. At the same time, the scientists do not possess much information about the reasons of extreme seasonal changes. Descent observations that can serve as the basis for this investigation started only in the middle of the 20th century with the invention of strong lenses and telescopes that can show the planet in details (Chown 33). Neptune  It is impossible to see Neptune with the unaided eye. As the result, its existence was initially assumed based on the basis of empirical observation and mathematical conclusions. It was first described by Alexis Bouvard in the middle of 19th century and the prediction was made because of perturbations of gravitation on Uranus. Neptune was discovered in 1989 by Voyager 2, that flew near this planet (Chown 50).  Nowadays, with the invention of the Hubble Space Telescope, the scientists are able to observe Neptune in more details. It is distanced from Earth and it seems to be very small even in the telescope. At the same time, Neptune is one of the biggest planets in the Solar System and it is 17 times larger than Earth  (Bennett 103).  It is necessary to mention the storms that happen on Neptune. NASA managed to discover the Great Dark Spot in 1989 during the expedition of Voyager 2. This natural phenomenon has the similar reasons as Jupiter’s Great Red Spot. The wind speed ups enormously near this spot. According to the observations, the planet experiences this anticyclonic storm more than 50 percent of time (Chown 51).  An interesting issue that should be mentioned in the description of Neptune is its internal heating. Even though the planet is the farthest from the Sun in the Solar System, its temperature is very high. The science can not give the definite answer concerning the reasons that lead to this internal heating  (Bennett 105). Pluto  Pluto is not considered to be the planet officially. It was excluded  in 2006 and defined as the dwarf planet from the ring of sky bodies of Neptune, the Kuiper belt in particular. It was discovered in the middle of 20th century and was considered to be the most distanced planet from the Sun (Chown 71).  There are five moons that relate to Pluto and that are known to the science. The largest is Charon,  the others are Hydra, Kerberos, Nix, and Styx. Some researchers claim that Charon and Pluto constitute the binary system. This notion refers to the phenomenon when the gravitation makes two astronomical bodies move on the barycenter orbit, which is not very usual in the traditional satellite-planet system  (Chown 73).  New Horizons has become the first robotic spacecraft that flew to Pluto in 2015. The expedition allowed scientists to state, that Charon is covered by cap on its north pole that can be the place for development of life (Chown 76-77). Thus, this dwarf planet will be researched in future as the place where life can start.