Ch. 1Study Guide ASTR 1307
Ch. 1Study Guide ASTR 1307 ASTR 1307
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This 3 page Study Guide was uploaded by Julian Sanchez on Saturday September 10, 2016. The Study Guide belongs to ASTR 1307 at University of Texas at El Paso taught by Noriega-Mendoza, Hector in Fall 2016. Since its upload, it has received 100 views. For similar materials see Elem Astronomy-Solar System in Science at University of Texas at El Paso.
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Date Created: 09/10/16
Chapter 1 Study Guide Elem Astronomy-Solar System 1307 Professor Hector Noriega Terms to know: 1. Inflationary Theory: the theory that the universe expanded faster during the big bag. 2. Dark Energy: an unknown force causing expansion of the universe. 3. North Star: a star seen in the northern hemisphere that allows for determination of the northern direction. 4. Circumpolar Stars: stars that never rise nor set. 5. Luminosity: Brightness of a star as seen from Earth. 6. Apparent Magnitude: Classifies brightness of stars as seen from earth (abbreviation: “m”) 7. Absolute Magnitude: the actual brightness of an object 8. One parsec: 3.26 light years away (abbreviation: “pc”) 9. Pythagoras Analogy: (6 Century BC) if the moon, planets, sun, and other worlds are spherical, then the Earth must be too. 10. Aristotle’s Argument: Earth is spherical because its shadow cast on the moon during a lunar eclipse is circular, NOT flat. 11. Heliocentric Model: sun-centered model of the solar system. th Crethed by Nicolaus Copernicus in the 6 Century (model accepted in 17 Century) 12. Geocentric Model: earth-centered model of the solar system. Created by Ptolemy in the 2 ndCentury AD 13. One Astronomical Unit (AU): Earths average distance to the sun; 149.6 km 14. Retrograde: the illusion that planets make loops as they cross the sky; the apparent backwards movement of planets. 15. Ptolemy’s Model: explanation of retrograde which involves revolutions around the earth, as well as smaller epicycles that create the planet loops. 16. Nicolaus Copernicus: astronomer from 6 century in Poland who came up with the heliocentric model nd 17. Ptolemy: created the geocentric model in the 2 century AD. 18. Tycho Brahe: Astronomer who made the most accurate description from before the telescope era. Observed elliptical orbits of the planets st 19. Kepler’s 1 Law: planets have elliptical orbits, with the sun at one of its focus points. 20. Kepler’s 2 Law: Planets speed up in their orbits as they approach the sun, and slow down as they recede. 21. Kepler’s 3 rdLaw: a smaller orbit means it orbits the sun in a shorter amount of time. 22. Eccentricity: Measure of how much the shape of an ellipse departs from that of a circle (basically how ovular an object is) 23. 4 Conic Sections: the result of cutting a cone at 4 different angles (i.e. Circle, Ellipse, Parabola, Hyperbola) 24. Perihelion: The closest position to the Sun as Earth orbits around it (147.1 km) 25. Aphelion: The furthest position to the sun as Earth orbits around it (152.1 km) Facts to know Universe: Is a network of filaments at its largest scale (composed of galaxies.) Constantly expanding and has no center Earth: Location: Virgo Supercluster, Local Group, Milky Way Is spherical, not flat (proven by Pythagoras Analogy, Aristotle’s Analogy, as well as modern evidence of the curvature such as the North Star). Has an elliptical (ovular) orbit and takes 365 days, 6 hours to orbit around the sun Has a tilt at 23.5 degrees, causing each of the 4 seasons (When the northern hemisphere points towards the sun, it is summer. When the northern hemisphere points away from the sun, it is winter.) Stars: Rise in the east, set in the west (however, stars near the Northern Star will never rise nor set) Emit light and energy. Usually have smaller objects orbiting around them. Have both an Apparent Magnitude (m) and an Absolute Magnitude (M) Can be seen to the naked eye if they have a magnitude less than 6 Magnitude: If m = M, then the star’s distance is equal to 10 parsecs away If m > M, then the star’s distance is greater than 10 parsecs away If m < M, then the star’s distance is less than 10 parsecs away An object with a small or negative magnitude number is brighter than an object with a large magnitude number. o Ex: Sun has a magnitude of -26.5, and Pluto has a magnitude of 14.9 Evidence of Earth’s Curvature: If the earth was flat, the north star would not change position no matter where on earth Pythagoras Analogy about spherical worlds Aristotle’s Argument about Earth’s circular shadow on the moon Evidence for/Facts on the Heliocentric Model: The telescope used by Galileo Galilea in the 17 century observed small objects orbiting large objects Discovery of the phases of planet Venus, as well as observations that it appeared to grow and shrink Favored CIRCULAR orbits Explained the retrograde seen by the planets Retrograde Is the apparent backwards/loop path made by PLANETS ONLY as they travel the sky Geocentric Model: o Explained with the epicycles as the planets orbited the earth Heliocentric Model: o Explained given the fact that the outer planets orbit slower than us, so as we pass them up, they appear to move backwards
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