Brief history of earth
Assignment on
“Brief History of Earth”
Course: ENV 107
1
Brief History of Earth
The history of the Earth concerns the development of the planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth 's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span.
Earth formed around 4.54 billion (4.54×109) years ago by accretion from the solar nebula.
Volcanic outgassing probably created the primordial atmosphere, but it contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of extreme volcanism and frequent collisions with other bodies. One very large collision is thought to have been responsible for tilting the Earth at an angle and forming the Moon. Over time, the planet cooled and formed a solid crust, allowing liquid water to exist on the surface.
Figure: Evolution of earth from a fireball
2
How the Earth formed
Scientists think that after the sun formed, about 4.55 billion years ago, it was surrounded by a disk-shaped cloud of dust and gases. As these particles of dust and gas orbited the sun, they collided with one another and stuck together. As more and more particles stuck together, they began to form bodies called planetesimals. In time, these planetesimals grew in size and formed the Earth and other planets.
During its early history, the Earth was struck many times by nearby planetesimals. These collisions, together with radioactivity and other processes like crystallization of the inner core, heated the primitive planet. These energy sources drive the dynamic Earth we know today, but, compared to the modern Earth, the energy available for heating Earth’s interior was orders of magnitude higher shortly after Earth formation. The expectation,
“Brief History of Earth”
Course: ENV 107
1
Brief History of Earth
The history of the Earth concerns the development of the planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth 's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span.
Earth formed around 4.54 billion (4.54×109) years ago by accretion from the solar nebula.
Volcanic outgassing probably created the primordial atmosphere, but it contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of extreme volcanism and frequent collisions with other bodies. One very large collision is thought to have been responsible for tilting the Earth at an angle and forming the Moon. Over time, the planet cooled and formed a solid crust, allowing liquid water to exist on the surface.
Figure: Evolution of earth from a fireball
2
How the Earth formed
Scientists think that after the sun formed, about 4.55 billion years ago, it was surrounded by a disk-shaped cloud of dust and gases. As these particles of dust and gas orbited the sun, they collided with one another and stuck together. As more and more particles stuck together, they began to form bodies called planetesimals. In time, these planetesimals grew in size and formed the Earth and other planets.
During its early history, the Earth was struck many times by nearby planetesimals. These collisions, together with radioactivity and other processes like crystallization of the inner core, heated the primitive planet. These energy sources drive the dynamic Earth we know today, but, compared to the modern Earth, the energy available for heating Earth’s interior was orders of magnitude higher shortly after Earth formation. The expectation,
Bibliography: http://www.space.com/54-earth-history-composition-and-atmosphere.html http://www.chabad.org/library/article_cdo/aid/1313/jewish/Discovery-of-Planet-Earth.htm http://www.universetoday.com/26659/earths-early-atmosphere/ http://en.wikipedia.org/wiki/History_of_the_Earth http://sci.waikato.ac.nz/evolution/EarthHistory.shtml 10