Thursday 13 October 2011

Universe

 
"The universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature. Scientific observation of earlier stages in the development of the universe, which can be seen at great distances, suggests that the universe has been governed by the same physical laws and constants throughout most of its extent and history. There are various multiverse theories, in which physicists have suggested the universe is one among many universes that likewise exist." (Wikipedia)
 


Universe is defined as, the whole system of existing things, including the earth and everything on it, outer space, and all heavenly bodies. Theories were developed to explain its origin. The Steady State, Plasma theory, Inflation Universe, Big Bounce, Cyclic Universe, Big Bang theory. Among them, the most widely known is the Big Bang Theory.
They say that everything was quiet until a cataclysmic explosion occurred hurling materials in all direction. this bang marked the birth of the universe. there were no galaxies and even atoms at that time except for a dense, very hot (estimated to be 10^32 degrees Celsius) and massive ball, the universe. As time passed, that ball started to expand. its rapid expansion caused it to cool and as it cooled its particles slowed down. The basic components of now began to form. For the next hours, it cooled up to ten million degrees Celsius and the protons and neutrons combined causing the formation of helium, the element that we can find now in the universe. The cooling didn't stopped and reached the temperature of 3000 degrees Celsius and electrons combined with nuclei to form neutral atoms. it took another billion of years for gravity to form the first stars and early galaxies.

Universe until now remains a mystery and man still seek for further information to answer the questions on their minds and they would not stop until they are contented.

Sun and Its Family


 
 
The development and acceptance of the heliocentric system (sun-centered/solar system), where the sun is considered as the center of the eight planets, helped the astronomers predict the position of the planets and its orbits. it has been indicated that the solar system consists of an ordinary star, the Sun, and around it revolved the planets and other heavenly bodies.




Planets were divided into two groups. First, the inner planets(Terrestrial planets). this consist of Mercury, Venus, Earth and Mars. Second, the outer planets(Jovian planets). Jupiter, Saturn, Uranus and Neptune are the planets that belong to this group. 
 
 
Below are the information about each planet:

Mercury- The smallest planet among the four inner planets. It makes one revolution around the sun in 88 earth's day. It is named after the messenger of the Greek gods. It is also considered as the hottest and coldest planet because there are no wind to carry heat from one region to another during night time due to very little atmosphere.
Inner Planets

Venus- the brightest star in the evening and in the morning sky. Because of its beauty, it is named after the goddess Venus. it is also considered as the twin sister of earth. its revolution is 225 earth days long. It has very dense atmosphere and opaque cloud cover and a green house that makes its atmosphere very hot.

Earth- the only planet that is capable for living organisms because of the atmosphere that enveloped it. It is also known as the Blue planet due to the abundance of its ocean. It revolves around the sun within 365 days.

Mars- this planet was named after the god of war. Its reddish color is due to the abundance of ferric oxide on its surface.It is smaller compared to earth and venus. It has low atmospheric pressure, lacks oxygen, scarcity of water and extreme change in temperature.



Outer Planets
 
Jupiter- the biggest among the planets. It was named after the ruler of Olympian gods due to its size. It is more liquid than gaseous and solid. Its atmospheres composition consist of hydrogen, helium, methane, ammonia and other molecules.

Saturn- A unique planet because of its rings. The slowest moving planet because of its slow pace. Its rings are composed of chunks of frozen water and rocks.  Its largest satellite is Titan.


Uranus- Discovered by William Herscbel in 1781. Its axis is tilted to 98 to the perpendicular of its Jupiter and Saturn because it has no internal source of heat.

Neptune- Its atmospheric composition is mainly hydrogen and methane with some helium and ammonia. Its largest satellite is Triton. It was named after the god of the sea.