Monday, October 29, 2012

Solar System

Solar System

Solar System
       Astronomers believe that the Solar System was formed from a cloud of gas and dust . The Sun that emits heat and light is the centre of the Solar System . The Sun is surrounded by eight  planets and other bodies such as natural satellites, comets and meteoroids .
       The nine planets starting from the one nearest to the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune(the furthest being Pluto not a planet anymore) .
       Each planet rotates about on its own axis . The rotation of the planets around the Sun is influenced by the strong gravity of the Sun making their orbits elliptical in shape .
       The Earth is one of the planets in the Solar System and it revolves about its own axis and also moves around the Sun following its own orbit .


    My name is Neptune . I am one of the planets of the Solar System . I am the eighth planet from the Sun . The distance from the Sun to me is 4504 million km . A space probe such as the Voyager 2 will take 12 years to reach me . I take 164.8 years to make one complete orbit around the Sun . The time I take to make one rotation on my own axis is 22 hours . Since the discovery of my existence in 1846, I have yet to complete one orbit around the Sun .
    I also experience the four seasons but the change from one season to another takes a long time because my orbit around the Sun is very slow . I receive very little light and heat from the Sun because I am very far away from the Sun . Therefore, it is very dark and very cold with a temperature below -150°C on my surface .
    I am 57 times the size of Earth and I have 13 natural satellites . Like Jupiter, I also have rings around me . Although I have 4 rings , they cannot be seen clearly .


    Before the invention of the telescope, man can only try to see planets like Mercury, Venus, Mars, Jupiter and Saturn with their naked eye . In 1781 Uranus was discovered by a British astronomer, William Herschel using a telescope he made himself . This discovery motivated people at that time to look for other planets .
    The diameter of Uranus is 51118 km and is the third largest planet in the Solar System . It takes 84 years to orbit the Sun and 24 hours to rotates on its own axis . The thick atmosphere in Uranus causes it to look bluish-green .
    One thing that is special about Uranus is that it rotates on its side and this cause it look like it is reclining ( resting in a horizontal position ) while rotating about its own axis .


    Saturn is the sixth planet from the Sun and the second largest planet in the Solar System . Its diameter is 120536 km . However its specific gravity is very small . If placed in the sea  it will not sink .
    Saturn rotates very fast about its own axis making one rotation in only 10 hours bit it takes 29½ years to make one orbit around the Sun . It is extremely cold with a temperature of -178°C .
    Saturn is known as the most spectacular planet because of the rings of ice and dust around it . It has 31 natural satellites . Among the natural satellites is one called the Titan with a diameter of 5150 km which is twice the size of Mercury .
(Specific gravity : Mass of any substance in relation to an equal volume f water.)


    Jupiter is the largest planet in the Solar System . Its diameter is 142984 km . It revolves around the Sun together with its 62 natural satellites .
    Jupiter is big and rotates fast needing only 9hours and 50 minutes to make one rotation about its own axis . However, the time it takes to make a complete orbit around the Sun is 12 years .
    Jupiter is a giant planet of gas . Its surface is covered with liquid and not rocks or land . The atmosphere is a layer of hydrogen gas and this is similar to that of the Sun .
    The Great Red Spot that can be seen on the surface of Jupiter are actually layers of gas that rise suddenly .


    Humans have already set foot on the Moon . Which planet will man’s next target be ? The answer is Mars . Its surface has volcanic craters and the plains (plateaus) are winding as though they are rivers .
    The characteristics of Mars include having a layer of atmosphere , temperature , period of rotation and changes of climate that are similar to that of Earth’s . This is why man have shown a keen interest in Mars . Actually Mars cannot support life and it will be strange for man to want to migrate there .
    Mars is a red planet and is the fourth planet from the Sun . Its diameter is 6791 km .  It takes 24 hours and 37 minutes to make one rotation about its own axis and 687 days to make one orbit around the Sun .
    The yellowish-red colour on the surface of Mars is due to the dust storms the blow for months .    


Earth is the planet we all live on . Although we assume that our Earth is very big , it is actually very small compared to the other planets in the Solar System . The average diameter of the Earth is 12735km .
The Earth is the third planet from the Sun . It takes 24 hours to make one rotation abut its own axis and 365¼ days to make one orbit around the Sun .
Earth is very special in the sense that it is a planet that has air and water . The layer of the atmosphere filters some sunlight to enable animals and plants to live safely on it . The distance of Earth from the Sun is neither too far nor too near . The Earth is also beautiful because it has four seasons .
The Moon is the natural satellite of the Earth , If the Moon is at the position exactly between the Earth and the Sun, the phenomenon called the eclipse of the Sun will occur . The Sun is blocked by the Moon and the Earth becomes totally dark . Have you ever seen an eclipse of the Sun ? 

    Have you ever seen a bright shinning object in the sky at dawn ? It is the planet Venus . It is the brightest object in the sky besides the Sun and the Moon .
    Venus has a diameter of 12103km . Venus is also the planet nearest to the Earth . The atmosphere on Venus is made up of a thick layer of carbon dioxide that completely covers the surface .
    Venus makes one complete orbit around the Sun in 224.7 days but its rotation about its own axis is very slow taking 243 days . The direction of rotation of Venus is opposite to that of the Earth’s . Venus rotates from east to west . If you were on Venus, you would see the Sun rising in the west and setting in the east
    However, man can never live on Venus because it is the hottest planet in the Solar System . The highest temperature is 462°C and no living thing can exist there .  


    Mercury is the planet nearest to the Sun . We can observe this planet by using an astronomical telescope . Mercury does not have air or living things on it .
    The diameter of Mercury is 4879km . Mercury takes 88 days to make one revolution around the Sun and 59 days to make one complete rotation about its own axis .
    Because Mercury has no atmosphere , its highest temperature is 427°C and the lowest is -173°C .
    The surface of Mercury is full of craters much like the surface of the Moon . Many big craters are named after famous artists like Beethoven, Mozart and others .