SGES 1302 INTRODUCTION TO EARTH SYSTEM

1. SGES 1302INTRODUCTION TO EARTH SYSTEM LECTURE 1: Introduction to Course The Universe

2. Course Info

3. SGES 1302INTRODUCTION TO EARTH SYSTEM • DR. NG THAM FATT • Room GB214, Tel:79674153, email:thamfatt@gmail.com • TESTS : (1=5 Oct); (2=24 Oct); (3=30 Nov); (4=21 Dec); Total 40% • FINAL EXAM (60%): Pre-requisite – 80% attendance • REFERENCES: • Butz, S.D. (2004): Science of Earth Systems. Delmar Learning, New York, 655 p. • Hamblin, N.K. (1992): Earth Dynamic System (6th Ed). MacMillan Publshing Co., New York, 647 p • Skinner, B.J., Proter, S.C. and Botkin, D.B (1999): The Blue Planet – An introduction to Earth System • White, I.D., Mottershead, D.N., and Harrison, S.J. (1994): Environment System: An Introductory Text (2nd Ed), Chapman and Hall, London, 495 p. • Tarbuck, E.J. and Lutgens, F.K. (2006): Earth Science (11th Ed). Pearson Prentice Hall, New Jersey, 726 p. • Hamblin, W.K. (1991): Introduction to Physical Geology. Macmillian Publ. Co., New York, 378 p.

4. Course Content

5. EARTH, SOLAR SYSTEM AND THE UNIVERSE Our Solar System (Sun, planets, moons & other smaller orbiting bodies) The Milky Way (billions of stars) The Universe (billions of galaxies) EARTH

6. Origin of the Universe • When we look up at the sky on a clear night, we are sharing a view that has been seen by our ancestors and countless people for thousands of year. • This creates a unique connection between all people who are living and have lived on Earth • Over time our with advancement of technology, understanding of our Universe has improved • The Big Bang

7. The Big Bang • The Big Bang is a cosmological model in which the universe has been expanding for around 13.7 billion years, starting from a tremendously dense and hot state. • The Big Bang release all known energy in the Universe, which began to spread from a central point. As energy spreads wider, it cooled to form clumps of matter, in theform of elements such as H and He. • Energy and matter continue to spread apart and the universe grew larger, clumps of dust and gas (molecular cloud) began to form. The clouds collapse to form the millions of stars.

8. The Universe • The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. This include all the stars, galaxies, and our solar system. • Based on observations of the portion of the universe that is observable, physicists attempt to describe the whole of space-time, including all matter and energy and events which occur, as a single system corresponding to a mathematical model. • To an observational cosmologists, the Universe most frequently refers to the finite part of space-time which is directly observable by making observations using telescopes and other detectors and using the methods of theoretical and empirical physics for studying the basic components of the Universe and their interactions. • A majority of cosmologists believe that the observable universe is an extremely tiny part of the "whole" (theoretical) Universe and that it is impossible to observe the whole Universe (infinite).

9. The Universe - Composition • The currently observable universe appears to have a geometrically flat space-time containing the equivalent mass-energy density of 9.9 × 10-30 g/cc. • This mass-energy appears to consist of 73% dark energy, 23% cold dark matter and 4% atoms. The exact nature of dark energy and cold dark matter remain a mystery. • Thus the density of atoms is on the order of a single hydrogen nucleus (or atom) for every four cubic meters of volume. • Prior to the formation of the first stars, the chemical composition of the Universe consisted primarily of hydrogen (75% of total mass), with a lesser amount of helium-4 (4He) (24%) and trace amounts of the isotopes deuterium (2H), helium-3 (3He) and lithium (7Li). • Subsequently the interstellar medium within galaxies has been steadily enriched by heavier elements. These are introduced as a result of supernova explosions, stellar winds and the expulsion of the outer envelope of evolved stars. • The temperature of the background radiation has steadily decreased as the universe expands, and now primarily consists of microwave energy equivalent to a temperature of 2.725 K.

10. The Universe - Shape • Currently, most cosmologists believe that the observable universe is very nearly spatially flat, with local wrinkles where massive objects distort spacetime, just as the surface of a lake is. • The universe has no spatial boundary according to the standard Big Bang model, but nevertheless may be spatially finite (compact). This can be understood using a two-dimensional analogy: the surface of a sphere has no edge, but nonetheless has a finite area. • If the universe were compact and without boundary, it would be possible after traveling a sufficient distance to arrive back where one began. Hence, the light from stars and galaxies could pass through the observable universe more than once.

11. The Milky Way Galaxy & the Milky Way

12. Galaxies • A galaxy is a grouping of millions or billions of individual stars, each of which sprang from the gaint molecular clouds or stellar nebulae. • Galaxies appears as a faint clouds of light when viewed through the telescope but their amazing forms are revealed by powerful telescopes. • There are 3 main types of galaxies: spiral, elliptical and irregular. • Spiral galaxy appears like a pin wheel surrounded by spiral arms. The nucleus appears like a large bulge of light (halo) which conststs of millions of stars. The spiral arms are composed of stars that rotate around the halo. • Elliptical galaxy has a nucleus and halo but no spiral arms. They are the most common type of galaxy. • Irregular galaxy has no well defined shape.

13. The Milky Way • The Milky Way is a barred spiral galaxy within the Virgo Supercluster. • The main disk of the Milky Way Galaxy is about 80,000 to 100,000 light-years in diameter, and outside the Galactic center, about 1,000 light-years in thickness. (1 light years = 9.5x1012 km) • The galaxy is estimated to contain 200 billion stars but this number might reach 400 billion if small-mass stars predominate. All the stars we see at night are located within the Milky Way. • As a guide to the relative physical scale of the Milky Way, if the galaxy were reduced to 65 km in diameter, the solar system would be a mere 1 mm in width.

14. The Milky Way • The term "milky" originates from the hazy band of white light appearing across the celestial sphere visible from Earth, which comprises stars and other material lying within the galactic plane. The galaxy appears brightest in the direction of Sagittarius, towards the galactic center. • The fact that the Milky Way divides the night sky into two roughly equal hemispheres indicates that the solar system lies close to the galactic plane. The Milky Way's visual absolute magnitude is −20.9 • Milky Way's mass is thought to be about 5.8×1011 solar masses. • It is extremely difficult to define the age of the Milky Way, but the age of the oldest stars in the Galaxy is currently estimated to be about 13.6 billion years, which is nearly as old as the Universe itself. • Many astronomer believe that there is a black hole at the center of the Milky Way.

15. The Milky Way The distance from the Sun to the galactic center is estimated at 26,000 ± 1400 light-years

16. Life Cycle of Stars • A star is a large, hot, glowing ball of gas that is powered by nuclear fusion. They begin as a stellar nebulla, a large cloud of dust and gas. • Gravitation attraction of the atoms within the stellar nebulla cause it to begin to collapse. As it collapse, it heats up and its density and pressure increase, forming a proto star. • Eventually it heats up to extreme temperatures, and the pressure within is high enough to start a fusion reaction (H atom fuse to form He, and releases energy). This is the main sequence stage of a star where the star begin to shine. • Eventually the star use up all its H, causes it to begin to expand and cool down (red gaint stage) and eventually burns itself out (white dwaft) and then cools (neutron star).

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