CHAPTER 2: THE PLANET EARTH
The earth is the only known planet in the solar system that supports life.
Its surface is made up of land and water bodies.
The evolution of the earth can be traced through various assumption
Including both theories and hypothesis which explain about the origin of the universe.
Some of the assumption that explain about the origin of the earth include
a) Big bang theory
b) Nebula hypothesis
c) Inter-stellar dust hypothesis
d) Creation theory
NEBULAR HYPOTHESIS (ORIGIN OF THE EARTH)
The Nebular Hypothesis explains the origin of the solar system.
It was first proposed by Immanuel Kant in 1755 and later modified by
Pierre Laplace in 1796.
The hypothesis states that the solar system formed from a cold, spinning cloud of gas and dust called the solar nebula.
MAIN IDEAS
The nebula was formed from an even distribution of gas in the Milky Way.
Gravity pulled the gas toward the center, increasing its rotation speed and flattening it into an accretion disk.
As matter collected at the center, pressure increased, causing the gas to warm up.
A hot ball of gas formed at the center—this became the protostar (the early Sun).
When the temperature and pressure became high enough, nuclear fusion began and the Sun was formed.
Outside the Sun, the remaining gas, dust, and rocks came together to form protoplanets, which later developed into the planets.
CRITIQUES OF THE NEBULAR HYPOTHESIS (BY PIERRE LAPLACE)
Collisions of cold particles cannot generate the large amount of heat Kant described.
Mutual collisions of particles cannot create motion in the primordial matter.
Random particle movement cannot produce the circular motion required for rotation.
The angular velocity (rotation speed) of the nebula cannot increase simply because the nebula grows in size, as Kant assumed.
The earth is the only known planet in the solar system that supports life.
Its surface is made up of land and water bodies.
The evolution of the earth can be traced through various assumption
Including both theories and hypothesis which explain about the origin of the universe.
Some of the assumption that explain about the origin of the earth include
a) Big bang theory
b) Nebula hypothesis
c) Inter-stellar dust hypothesis
d) Creation theory
NEBULAR HYPOTHESIS (ORIGIN OF THE EARTH)
The Nebular Hypothesis explains the origin of the solar system.
It was first proposed by Immanuel Kant in 1755 and later modified by
Pierre Laplace in 1796.
The hypothesis states that the solar system formed from a cold, spinning cloud of gas and dust called the solar nebula.
MAIN IDEAS
The nebula was formed from an even distribution of gas in the Milky Way.
Gravity pulled the gas toward the center, increasing its rotation speed and flattening it into an accretion disk.
As matter collected at the center, pressure increased, causing the gas to warm up.
A hot ball of gas formed at the center—this became the protostar (the early Sun).
When the temperature and pressure became high enough, nuclear fusion began and the Sun was formed.
Outside the Sun, the remaining gas, dust, and rocks came together to form protoplanets, which later developed into the planets.
CRITIQUES OF THE NEBULAR HYPOTHESIS (BY PIERRE LAPLACE)
Collisions of cold particles cannot generate the large amount of heat Kant described.
Mutual collisions of particles cannot create motion in the primordial matter.
Random particle movement cannot produce the circular motion required for rotation.
The angular velocity (rotation speed) of the nebula cannot increase simply because the nebula grows in size, as Kant assumed.