Thursday 8 March 2012


ORIGIN OF SOLAR SYSTEM- Theories

The solar system (Disigned by http://www.learningbygrace.org/releases/pluto.php)
                                                                        According to modern research, there are eight planets, ninth planet which was PLUTO is not considered as planet. Therefore, eight planets and the sun are the main bodies of the solar system. Whereas, planets are concerned, on the basis of their location they can be divided into two groups. (i) Inner planets (Terrestrial) which include Mercury, Venus, Mars and Earth. They are of small size, high density, their composition is silicates, metals and their rate of rotation is very high. (ii) Outer planets (Jovian) which include Jupiter, Saturn, Uranus and Neptune. These planets are of large size, low density and their rate of rotation is very slow.
                                                             The theories of origin of solar system can be divided into two groups:
ð   Evolutionary Theories: The theories, which suggest that planets are formed during the evolution of sun, are called evolutionary theories.e.g: Nebular Hypothesis.
ð   Catastrophic Theories: The theories, which suggest that planets are formed by some special accidents, such as by collision of two stars.e.g: Planetesimal, binary star and Gaseous Tidal Hypothesis.
NEBULAR HYPOTHESIS: A vast cloud of hot gas is called nebula. The nebular hypothesis, developed by Immanuel Kant in 1755 and Laplace in 1796. According to this hypothesis, “the sun and planets have formed from disc-shaped rotating nebula”.

                                              The nebular hypothesis may be summarized as the nebula rotated and contracted, rings of gas were cast off at various stages from which the planets subsequently condensed.
PLANETESIMAL HYPOTHESIS: According to Moulton (1901) and Chamberlin (1901) the solar system originated from matter, which was in form of tiny dust, grains called “Planetesimals”.
                                                                             The planets evolved from a cloud of planetesimals, which revolve around the sun. The planetesimals, the tiny cosmic fragments collided with each other and united together to form larger bodies, which became planets and satellites revolving around the sun.
GASEOUS TIDAL HYPOTHESIS: Jean (1919) and Jeffrey (1925) postulated gaseous tidal hypothesis. This hypothesis states “A big star during its course of wandering in the space approached the sun and caused violent tidal distortion in the sun by its very strong gravitational pull”.
                                                                                                    As it came very close to the sun, parts of the sun affected by strong tide were pulled away in the form of a spindle shaped filament, which was in unstable state. Then, as the big star receded away, this unstable filament broke away into pieces of hot and gaseous masses. Few of them were carried away along with the receding star; while major bulk of them fell into the gravitational field of sun. They formed globular masses orbiting the sun. The bigger masses gradually cooled down and concentrated to planets. The smaller masses solidified into satellites. One of the planets further broke away into pieces called asteroids/planetoids.
BINARY STAR HYPOTHESIS: This hypothesis was put forwarded by Lyttleton in 1938. Our solar system was born from one of these star pairs, which consisted of the sun and another smaller star known as the companion star.
      A huge-sized third star came into the region of this paired stars and caused tidal explosions in the companion star which was completely disrupted, When the third star came close to the companion star some parts of the companion star, were carried away along with the third star which eventually receded away. The rest fell into the sun’s gravitational control, these parts retained by the sun revolved round it and gradually cooled down to form the planets.

CLICK THE LINK BELOW FOR MORE NOTES AND KNOWLEDGE ON GEOLOGY

Galaxy, Stars, Asteroids, Planets, Satellites:
v   Galaxy (Greek = galaxies means milky): It is massive, gravitationally bound system that comprises of stars, stellar, remnants and interstellar material.
Galaxies as per of two sizes:
ð  Dwarfs: about ten millions stars.
ð  Giant: hundred trillion stars.
  There are about 170 billion galaxies in the universe.
v   Stars: Star is a massive, luminous, ball of plasma that is held together by gravity.
v   Asteroids: Class or combination of various objects present in the solar system but lying in the orbits to various planets.
v   Planets: Celestial objects that are present around sun (they revolves round sun) and they capable of generating their own gravitational field.
v   Satellites: Satellites are the objects placed into orbits around planets.
Satellites are of two kinds:
                                       => Natural satellite.       E.g.: Moon.
=> Artificial satellite.    E.g.: Sputnik in   1957(Russia)

CLICK THE LINK BELOW FOR MORE NOTES AND KNOWLEDGE ON GEOLOGY
http://geopedia-geology.blogspot.com 

ABOUT THE UNIVERSE— BIG BANG THEORY:
                                                                                                                   This theory explains the early development of universe. Georges first proposed this theory in 1927. According to big bang theory “ the universe was once in an extremely hot and dense state, which expanded rapidly. This rapid expansion caused the young universe to cool and resulted in its present continuously expanded state”.

CLICK THE LINK BELOW FOR MORE NOTES AND KNOWLEDGE ON GEOLOGY
http://geopedia-geology.blogspot.com 

Introduction and scope of geology:
                                                                    Geology is a Greek word (geo means earth+ logos means science/study).
                                                                  “Geology is a science which deals with all the features of the earth’s surface and with the origin, composition, structure and inhabitants of the earth”.
                                                                                             Geology is a broad field and it is divided into several branches:
Ø Physical geology
Ø Engineering geology
Ø Structural geology
Ø Petrology
Ø Paleontology
Ø Stratigraphy
Ø Mineralogy
Ø Historical geology
Ø Economic geology
Ø Mining geology

  Geology deals with the study of earth. It is a science, which covers all aspects related to earth like it undertakes the study of matter that constitutes the earth. It has a broad scope because it also covers the study of structure, composition, physical properties, and history of Earth. It also discusses various processes of earth like how it was formed, how it moves and how it has changed over a period of time. Geology is also linked with industrial study and engineering because industrial studies deals with the mineral extractions which are found on earth and engineering is closely linked with geo technical aspects of earth.

CLICK THE LINK BELOW FOR MORE NOTES AND KNOWLEDGE ON GEOLOGY
http://geopedia-geology.blogspot.com/