Author Question: Briefly explain the current theory of Earth's origin, including how and why it came to be ... (Read 23 times)

jazziefee · **on:** Jul 15, 2018

Briefly explain the current theory of Earth's origin, including how and why it came to be differentiated
by composition. What will be an ideal response?

Question 2

Describe how the universe, galaxies, stars, and chemical elements formed What will be an ideal response?

kardosa007 · **Reply #1 on:** Jul 15, 2018

Answer to Question 1

In the solar nebula, gases and solid particles condensed in localized eddies and then accreted into
planetesimals. These bodies collided and grew until they became planets. The planets nearer the Sun
were small and composed of rock and metallic elements. One of these was Earth. Heat was generated
by meteorite impacts, gravitational compression, and nuclear reactions. The heat caused the material to
melt. Since it could now move, dense metals sank to the core and denser silicates to the mantle.
Lighter silicates rose to form the crust.

Answer to Question 2

Scientists believe that the universe originated with the Big Bang approximately 14 billion years ago.
At the moment of the Big Bang, there was only energy, no matter. In the first second following the Big
Bang, the four basic forces separated, and the universe experienced enormous expansion. Galaxies and
stars came together, and the chemical makeup of the universe changed. In the early universe, the only
chemical elements were hydrogen and helium, but now 2 of the universe is all other elements by
weight.