Origin of earth - big bang hypothesis, PL-SQL Programming

ORIGIN OF EARTH -

BIG-BANG HYPOTHESIS -

  • Origin of life is linked to origin of earth.
  • Cosmos, the Universe originated 10-20 billion years ago by Big Bang (thermonuclear explosion).
  • Its part, a galaxy, (e.g., our Milky Way) comprises millions of stars, (our Sun is one of those).
  • Sun, its planets and satellite constitute the solar system.
  • Our earth is the 3rd planet with rocks, water & atmosphere.
  • It began as gaseous clouds of metals and non-metal atoms, later condensed to form surface rocks and boiling fluid core with gaseous atmosphere.

Chronology of events

Origin

Ago (Billion yrs)

Universe

10-20

Solar system

4.6

Earth

4.5

Oldest surviving rock

4.3

Life (Heterotrophs)

4.2-3.9

Old rock

3.9

Chemosynthetic

procaryotes

 

3.8-3.5

Oldest microfossils

(Cyanobacteria)

 

3.3-3.5

Photosynthetic procaryotes

 

3.5-3.3

Eukaryotes

1.6-1.5

NEBULAR HYPOTHESIS -

  • Earth is formed by gradual condensation of interstellar dust, from which our entire solar system is presumed to be formed.
Posted Date: 10/8/2012 8:25:37 AM | Location : United States







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