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Earth's Formation Help

By — McGraw-Hill Professional
Updated on Aug 30, 2011

Earth’s Formation

In 1755, Immanuel Kant offered the idea that the solar system was formed from a rotating cloud of gas and thin dust. In the years since then this idea became known as the nebular hypothesis . The clouds that Kant described could be seen by powerful telescopes. The Hubble Space telescope has sent back images of many of these beautiful formations called nebulae .

NASA has many images of nebulae photographed from the Hubble Space Telescope. The following websites will give you an idea of the different nebulae that scientists are currently studying:

http://hubble.nasa.gov http://science.msfc.nasa.gov www.nasa.gov/home/index.html http://hubblesite.org/newscenter

The most outstanding of these might be the Horseshoe and Orion nebulae. These beautiful cosmic dust clusters allow space scientists to study the differences between cosmic cloud shapes, effect of gravitational pull, and other forces that influence the rotation of these dust clouds.

It’s likely that when the Earth was first forming in our young solar neighborhood, it was a molten mass of rock and metals simmering at about 2000°C. The main cloud ingredients included hydrogen, helium, carbon, nitrogen, oxygen, silicon, iron, nickel, phosphorus, sulfur, and others. As the sphere (Earth) cooled, the heavier metals like iron and nickel sunk deeper into the molten core, while the lighter elements like silicon rose to the surface, cooled a bit, and began to form a thin crust. Figure 1-4 shows the way the elements shaped into a multilayer crust. This crust floated on a sea of molten rock for about four billion years, sputtering volcanic gases and steam from the impact of visitors like ice comets. Time passed like this with an atmosphere gradually being formed. Rain condensed and poured down, cooling the crust into one large chunk and gathering into low spots, and flowing into cracks forming oceans, seas, lakes, rivers, and streams.

Planet Earth

Fig. 1-4. The Earth has four main layers.

Practice problems of this concept can be found at: Planet Earth Practice Test

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