a science that examines the earth, its form and composition, and the changes it has undergone and is undergoing involves the knowledge of what happened before and the events occurring within the atmosphere requires not only a study of the materials found on earth but an understanding of the various geologic processes aims to develop an understanding of the earth’s materials and how these materials were changed and modified through the action of natural forces over a period of time Geology as a Discipline
Two areas of Geology:
Physical Geology – deals with the study of the materials composing the earth and the processes and phenomena that operate beneath and upon its surface. Historical Geology – deals with the study of the evolution of the earth.
Physical geology precedes historical geology because we need to know how our own planet works before we attempt to open its past. Astronomical Studies
About the Earth
the first to suggest heliocentric universe but was rejected
the first Greek to advocate a sun-centered universe (heliocentric)
suggested that earth rotates upon an axis and revolves around the sun in its orbit also advocated heliocentric theory
advanced the geocentric theory which describes the individual apparent path that the sun, moon, planets, and stars follow while moving around a stationary earth
emerged and revived the first great heliocentric
responsible for building pointers used to measure the location of heavenly bodies. Galileo Galilei
invented the first astronomical telescope used to support the Heliocentric Theory Johannes Kepler
discovered the three fundamental laws of planetary motion which describes the Copernican Theory Sir Isaac Newton
Discovered the laws of gravitation and motion that makes Kepler’s and Copernicus’ explanation be understood. Age of the Earth
The earth and meteorites were formed from the same materials (solar nebula) and presumably at the same time. Due to this, the earth is inferred to have formed at about 4.55 billion years ago.
The oldest terrestrial rocks that have been accurately dated directly are close to 4 billion years old and the oldest rocks on each continent are found to be generally between 3.6 and 3.9 billion years old. Size of the Earth
Erastosthenes calculated the size of the earth by measuring the distance between a deep well to Syene and Alexandria and the angle of the moon and sun in Alexandria on the first day of summer. Through mathematical calculation, he found the angle of the moon and sun to be a little more than 7° which is almost 1/50th of the complete circle.
Before, it was believed that the earth was perfectly round. However, Isaac Newton proved that the earth’s circumference at the poles was less than the circumference at the equator. Its diameter at the equator is about 43.2 greater than diameter at the poles. Scientists agree that the slight bulge is caused by rapid rotation of the earth on its axis which makes the earth’s shape spherical.
Shape of the Earth
The degree of latitude is longer at the vicinity of the poles than near the equator. Analysis shows that the resulting shape of the earth is an oblate spheroid. This means that the earth is flat at the poles while the the equitorial regions are slightly bulging, hence a person at one end of the poles would be nearer the earth’s center than he would be at the equator. The earth’s oblate shape and its rotation reduce the weight of an object at the equator than its weight at the poles. The equatorial bulge also produces slight disturbances on the motions of the moon and artificial satellites. Proofs of the Shape of the Earth
1) Several planes made to go around the largest circumference of the earth, each starting in a different direction, showed that all flights were of equal distances. 2) Persons aboard a ship observe that a passing ship receding...
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