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Our solar system includes the Sun, 9 planets, satellites of planets, asteroids, comets, meteoric bodies and cosmic dust, all located within the scope of the gravitational influence of the Sun.
The Sun is the central body of our solar system, a scorching-hot plasma ball weighing 2 x 1030 kg and with a radius of 696 thousand km. Hydrogen makes up about 90% of its weight, helium almost 10% and other elements, less than 0.1%. The source of solar energy is from continuous nuclear reactions, converting hydrogen into helium. The structure of the Sun includes a nucleus, internal and external layers and a solar "atmosphere," in which there is the chromosphere and solar corona. The bottom layer of solar atmosphere is named the photosphere.
The solar nucleus has a temperature of about 14 million degrees, Celsius. An interaction between the internal and external layers of the Sun causes a transfer of energy from the nucleus to the solar atmosphere to occur. The temperature of the solar corona is about 1 million degrees, Celsius. Almost all of the electromagnetic radiation from the Sun emanates from the photosphere. Solar activity in the photosphere manifests itself as sun-spots and as solar flares, which rise to great altitudes above the surface of the Sun.
The solar atmosphere is very dynamic: in it, chromospheric flares and solar prominences are observed, as is the continual death and rebirth of the solar corona, which emits substances into interplanetary space (solar wind).
The Sun is the main source of energy for all manner of processes set in motion on our planet. It provides all of the natural light and heat, without which, life on the Earth (as we know it) is impossible.
The planets of our solar system are divided into two groupings: inner and outer. The inner four are relatively small planets, named Mercury, Venus, Earth and Mars. At and near the orbit of Mars is an extensive belt in which there are thousands of small, planet-like-objects called asteroids. Beyond this belt and further from the Sun are the outer planets - four giants: Jupiter, Saturn, Uranus, Neptune, and finally, a very small planet, Pluto, situated on the periphery of our solar system. The physical characteristics of Pluto are qualitatively different from the characteristics of it's nearest neighbouring planets - giants, and consequently, it cannot be physically related to that part of that grouping. Only its great distance from the Sun places Pluto in the outer planets grouping.
The inner planets have not only much in common, but also essential distinctions: Mercury is the planet that is the heaviest and nearest to the Sun. It has NO atmosphere. Mars has a rarefied atmosphere. Very similar to the Earth in size and weight, Venus has a dense and very hot atmosphere (temperature of a surface of Venus about 400 degrees (C), which consists basically of carbon dioxide (CO2), and excludes the existence of the type of life thus-far found on earth.
The planets in our solar system are accompanied by satellites. The Earth has 1 satellite - the Moon; Mars - 2; Jupiter - 12; Saturn - 10 (not including its rings); Uranus - 5; and Neptune - 6,.
Planet Earth is a unique planet of our solar system:
it has oceans, it is only planet on which we know life exists. However,
life is a natural stage in the of development of matter, and therefore
Earth cannot be considered as unique, that is, the only inhabited planet
in the Universe.
Information provided by HDNO: http://www.oceansatlas.com/unatlas/about/ContactInfoForHDNO.html