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Solar System and the outer space
by Evelyn Rose
Category : Education |
Solar system is one of the most interesting topics discussed in school because of the countless colorful heavenly bodies occupying the universe and the idea that there is actually something else outside of our world. We live in a universe of almost unimaginable size. Our own galaxy, the Milky Way, is a typical spiral galaxy. This means is looks like a great swirling whirlpool with spiral arms extending out from the center. The Milky Way galaxy is 100,000 light years in diameter and our own star.
The chief member of our solar system is the Sun, and its keeps planets in order by its gravitational pull. It is believed that the sun, the center-piece of the solar system, was born five billion years ago, emitting heat and light non-stop, and it is expected to do so for the next five billion years. The sun is the richest repository of electromagnetic energy, in the form of heat and light. The sun contains 99.85 per cent of all the matter in the solar system. Sun is a bright star and exudes heat and light through nuclear fusion. The Sun, lies on the edge of one of the spiral arms. Sun is about 30,000 light years from the center of the Milky Way galaxy and takes 225 million years to complete one orbit around the galactic center.
A planet, according to the IAU, is a spherical object that orbits the Sun. It must have no small objects near it. Till last year we all knew that there were nine planets in the Solar System, but now Pluto is officially an outcast. This is because Pluto does not fit the International Astronomical Union’s (IAU) definition of a planet. It is now a dwarf planet. The planets of our Solar System are generally divided into two groups. Inner planets include Mercury, Venus, Earth and Mars. The outer planets include Jupiter, Saturn, Uranus, Neptune and until recently the dwarf planet Pluto. The inner planets are all characterized by having solid surfaces and are relatively small compared to the outer planets. The outer planets are all characterized by not having a solid surface and are often referred to as gas giants. The inner and outer planets are also separated by a band of asteroids orbiting between Mars and Jupiter.
Comets, meteors and asteroids can also be found orbiting the sun in large numbers from the outer reaches of the Solar System to very close to the Sun. Trans-Neptunian objects and other small celestial objects also come under this category. Comets are balls of frozen liquids and dust which often follow eccentric orbits for outside the orbit of Dwarf Planet Pluto and only display their characteristic tails when their orbit brings them closer to the Sun. Asteroids and meteors are both made mainly of rock. There are mainly found in the region between Mars and Jupiter. They are rocky objects that could span several hundred kilometers or be small like dust. Ceres is the largest asteroid. The difference between asteroids and meteors is their size, meteors can be as small a grain of dust, asteroids can be miles in diameter and are sometimes called planetoids.
Outer space and the solar system may be a very interesting topic but its long history of theoretical and practical developments can fuel a lot of questions. Technological advances in the form of telescope and spacecraft have helped scientists to obtain a lot of information about the solar system. It’s not a static situation out there, and as new technologies develop here, new and exciting facts about the solar system are uncovered.
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