By PragyanSharma Polavarapu
Our aim in these articles is mainly the study about the various living systems of planet Earth—our Mother Earth. Before attempting this we have to know about the place of planet Earth in solar system ,its age and history and also a little about its air(the Atmosphere), its oceans, seas, lakes, rivers etc (the Hydrosphere) and its world of mountains and hills and land,its stones and sand (the Lithosphere).
The sun around which earth rotates along with eight other planets and their moons since “endless time” is a huge sphere of 98% Hydrogen and Helium gases (in their ionized plasma form) with its surface layers burning at about 6000 degrees centigrade and interior having temperatures of ten million degrees with endless nuclear reactions. Nuclear fusion reaction takes place in interior of sun every moment and energy equivalent to millions of atomic bombs is produced and radiated into space every second! Eeven the surface of burns at 6000 degrees !( The melting temperature of iron is just 1500 degrees and H2O boils only at 100 degrees centigrade).scientists say that sun can exist with this rate of energy release for another four and half billion years!
The stone sphere of earth has diameter of 7900 miles.Each of the other eight planets are either a little bigger or smaller. Compared to the earth,the sun is a sphere of gaseous and plasma matter with diameter of 864,600 miles. The sun weighs 333,000 times more than the sphere of earth. Scientists say that 1,300,000 earths can fit inside the sun!
Scientists tell that sun formed from an un-imaginably big cloud of huge mass of gas and cosmic dust . After slowly gathering colossal quantities of material from the surrounding hydrogen and dust cloud for about 4500 million years(450 crore years) it went through an “imploding” stage— (matter falling at violent speed towards a gravitational center)— and a star with a million degree hot core formed in which nuclear fusion reactions started. Hydrogen ions fused to create helium ions and also colossal quantities of energy at millions degrees heat and other radiations. Thus was the sun created.
A colossal flat cloud of matter consisting of white hot gaseous and dusty matter rotated around sun and was dragged by the sun around itself. Earth and the other planets were formed from this white hot gas and dust cloud and appeared like white hot liquid drops of melted metals and melted stone . The planets started moving in elliptical orbits around the sun at distances of hundreds of millions of miles.
All the the planets and perhaps the moons were thrown to a big distance (hundreds of millions of miles) by the centrifugal force created by the sun at time of creation. These distance are really small compared to the distances of the faraway cosmic bodies like galaxies and stars. The earth and other planets and moons could not escape the terrific gravity of sun. The planets with their moons rotate endlessly around sun at a very great distance but are firmly bound to sun for endless time due to terrific invisible gravitational pull. The comets move around the sun ,in extremely long orbits requiring decades of time. The comets originate in an extremely cold area at border of our solar system called “Oort cloud” where thousands of big and small icy objects (some round and some of irregular shapes) exist and take long elliptical routes for century-long journeys around the sun. The comets are a few hundred meters or a few kilometers long and are thought to be concrete-hard sand and ice masses melting and disintegrating when they move near to the sun in their extremely long elliptic orbits
The most distant planets and comets are generally very cold masses at nearly “minus 100 to minus 200 degrees” temperatures. But all these move in strict solar orbits controlled by the terrific gravity of sun. There are big and small stone pieces called meteors in the vicinity of some distant planets but all floating in orbits and now and then disturbed by the gravity from heavy planets passing nearby heavy during their orbits round the sun. Some small stone-size meteors get attracted by earth’s gravity and burn up in our atmosphere as they enter earth’s air envelope at terrific speeds of 20 or 30 kilometers per second.
Now onwards all our discussion is limited to planet earth. But we move to a time 4500 million years back(450 crore years) in our imagination. Though temperature deep inside the sun may be ten million degrees and though the heat on the surface too may be 6000 degrees centigrade, it is horribly cold in cosmic space —thousands of millions of miles from the stars and sun. The temperatures in the dark, silent and cold cosmic space may be “minus 200 degrees” or even far colder –quite near to the “Absolute Zero”( minus 273 degrees)!
Though the earth and other planets in their formative stage existing near the sun were very hot , they cooled quickly in course of a few million years when they moved into faraway orbits at hundreds of millions of miles distance from the sun. In the beginning the planets including our earth were like white hot liquid drops of molten metal and molten stone. But all of them soon lost all that heat by radiation into space . Some planets moved so far away from sun that they become extremely cold
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