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General Physical Geology and the Formation of the Solar System Lecture. With Ms. Terry J. Boroughs. Figure I.2A. Figure I.2B. What is Geology and/or Earth Science?. Geology is the study/science of the Earth Including the Composition of the Earth, e.g.
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General Physical Geology and the Formation of the Solar System Lecture With Ms. Terry J. Boroughs
What is Geology and/or Earth Science? • Geology is the study/science of the Earth • Including the Composition of the Earth, e.g. • Rocks, Minerals, Internal Layers, etc. • Including the processes that affect the surface and the interior of the Earth, e.g. • Volcanism, Earthquakes, Plate Tectonics, etc. • Historical Geology emphasizes the history of the Earth, whereas Physical Geology emphasizes the physical aspects of the Earth
Four “Spheres” of Earth Science / Geology • Geosphere / Solid Earth: • The physical Earth, rocks, etc. • Hydrosphere: • The sum total of water on the Earth; Water, water bodies, and the influence of water on the Earth. For example, Oceans, lakes, etc. • Biosphere: • The sum total of biological material on the Earth; plants, animals, and their influence on the Earth. • Atmosphere: • The envelope of gasses that surround the Earth, thus protecting it from some of the more harmful effects of solar radiation. The atmosphere can interact with the Earth’s surface in the form of climate, winds, etc. These “spheres” can interact in many different ways to affect the Earth’s Surface.
Principle of Uniformitarianism • Also known as the principle of uniformity • “The Present is the Key to the Past.” • Present day knowledge about geological processes and/or events is used to investigate and explain ancient events. • For example, one can observe the processes associated with an eroding river and look for similar features in an ancient landscape. • In other words, our present understanding of geology is the key to unlocking the past.
The Scientific Method • The Scientific Method is one of many ways that we can view the world around us. • The Scientific Method is a method of investigation, a method used to systematically and scientifically investigate the world around us, using qualitative and quantitative data. • This method can be used in conjunction with any field of science, such as: Chemistry, Physics, Mathematics, Biology, and Geology, and even to some extent in fields such as Psychology, Anthropology, Archaeology, and Sociology. • It can also be used in our daily lives!
The Scientific Method • A. Ask Questions • B. Study previous work done concerning your question(s) so that you will have some idea of the possible answer(s) to your question(s). • C. Propose a Hypothesis or tentative explanation or prediction of experimental observations and perform experiments designed to eliminate erroneous observations. • D. Collect Qualitative (information consisting of non-numerical observations about the problem) and Quantitative (numerical information) data concerning your problem. • E. Check that your data is Reproducible under constant conditions by retesting your hypothesis. • F. Summarize your observations in the form of a Theory (a unifying principle that explains a body of facts and the laws based on them) or a Law if the theory is always true. A Law can also be written mathematically.
A Historical view of Astronomy • Scientific knowledge is often a cumulative effect, where knowledge and understanding accumulates over time. • A great example of this accumulation of knowledge is a review of some of the major discoveries in Astronomy over time, leading up to our present-day understanding of the Solar System and Universe.
A Historical view of Astronomy • Early Greeks: 600 B.C. – A.D. 150 • The Early Greeks held the GEOCENTRIC (“Earth-centered”) view that the Earth was the center of the universe and was orbited by the moon, sun, and the known planets (at that time) – Mercury, Venus, Mars, Jupiter, and Saturn. Beyond the planets was the CELESTIAL SPHERE (a transparent, hollow sphere on which the stars traveled daily around the Earth.)
A Historical view of Astronomy • Early Greeks: 600 B.C. – A.D. 150 • Ptolemy’s Model: Ptolemy created a model of the universe in which the planets were moving in circular orbits around a motionless Earth. This precise model also accounted for the observable motions of the planets. • Ptolemy described EPICYCLES (small circles) moving along DEFERENTS (large circles) to explain the apparent RETROGRADE motion of Mars.
Geocentric or Ptolemaic model of the Solar System and/or Universe,Figure 15.3A
Apparent Retrograde Motion of Mars, Ptolemy’s Model, Figure 15.3B
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Nicolaus Copernicus: Copernicus was convinced that the Earth was a planet and that the daily motions of the heavens were better explained by a rotating Earth, with the Sun at the center of his model. His model still used circles and epicycles in the manner described by Ptolemy.
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Tycho Brahe: Without the use of telescopes, Tycho Brahe systematically measured the location of heavenly bodies, such as Mars. These extremely precise observations were the foundation of the work done by Johannes Kepler. • Brahe did not agree with Copernicus’s Sun-centered model due to the apparent lack of STELLAR PARALLAX. However, this apparent lack of parallax was due to the extreme distances to the stars and the absence of a telescope.
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Johannes Kepler: A former assistant to Tycho Brahe, Kepler used Brahe’s observations for the foundation of his three basic laws of planetary motion. Kepler realized that the orbit of Mars was not a circle but an ellipse and that the orbital speed of Mars varies with its proximity to the Sun.
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Johannes Kepler: • Three basic laws of planetary motion. • 1st Law: The planets follow an elliptical path around the Sun, which represents one of the foci of the ellipse. • 2nd Law: As the planets revolve around the Sun, they sweep out an equal area in equal time intervals. • “The orbital periods for the planets and their distances to the Sun are proportional.” The Earth acts as a reference point, so that orbital periods are measured in Earth years, planetary distances are expressed in terms of the Earth’s mean distance to the Sun in astronomical units (AU) (~150 million kilometers or ~93 million miles.)
The planets sweep out equal areas in equal time periods due to gravity,Figure 15.9
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Galileo Galilei: Galileo also held the Sun-centered or Copernican view of the universe. He also constructed his own telescope which allowed him to view the following: • 4 moons of Jupiter; the planets are circular disks rather than points; Venus has phases just like the Moon indicating that it too orbits the Sun; the Moon’s surface is varied and cratered; and sunspots on the surface of the Sun. • The Inquisition sentenced Galileo to house arrest for proclaiming doctrines contrary to religious doctrine.
Heliocentric model depiction of the phases of Venus,Figure 15.12B
A Historical view of Astronomy • The Birth of Modern Astronomy: (1500’s to 1700’s) • Sir Isaac Newton: Newton determined that the concept of inertia (once an object is set into motion it will stay in motion) and would allow a moving object to continue moving at a uniform speed and in a straight line. This concept later became Newton’s 1st Law of motion. • Newton also conceptualized that the force of gravity helps maintain the orbit of planetary and lunar bodies. “Every body in the universe attracts every other body with a force that is directly proportional to their masses and inversely proportional to the square of the distance between them.”
