Origins and Structure: Earth and It’s Oceans . Unit 1: Chapter 2 in Garrison 6 th Edition. The Formation of Earth. The Big Bang – 14 BYA Mass and energy began to expand from a geometric point. Evidence: Galaxies are still moving away from us at a speed proportional to their distance.
Unit 1: Chapter 2 in Garrison 6th Edition
Mass and energy began to expand from a geometric point.
Evidence: Galaxies are still moving away from us at a speed proportional to their distance.
dust) begins to shrink and heat up.
Protostar forms as it flattens and condenses at
the center into a knot of gases
Nuclear fusion, hydrogen fuses to form helium,
begins at 10 million degrees Celsius = energy
1) Condensing mass began to spin
2) The nebula absorbed heavier atoms passing by.
outer material = planets (protoearth)
The Sun and planets formed by accretion
(smaller particles in the spinning nebular cloud clumping together to form larger objects)
Why? Cooler temperatures allowed methane
and ammonia ices to congeal together.
ex) Mercury which is mostly iron.
Fig. 1.8, p. 8
We are here
Density Stratification (4.6 bya)
Recently some researchers have suggested that ice meteorites could have been an important source of water, although this view has been challenged.
Figure 2 – 07
There was no oxygen (it would be made later by photosynthesis), and there were methane, ammonia, and high amounts of carbon dioxide.
Fig. 1.12, p. 12