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Astro Study Guide

# Astro Study Guide - Astro Study Guide Scientific Method The...

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Astro Study Guide Scientific Method- The procedure by which scientist construct their ideas about the universe and its contents. A scientist proposed an idea(hypothesis) about some property and tests the hypothesis by experiemtn. The experiments results either support or refute it. Astronmers cannot experiment directly with their subject matter making the method hard. Parralax- it is the apparent shift of an object against the background that is caused by a change in the observer's position. angle R/2 π d D= 360degrees x R/ 2 π p 60x60x60xR/2 π d= 1/P(arcsec) Beginning of Modern Astronomy Motion of Planets and early Theories Tyco Brahe - made the most accurate pretelescopic measurements - model said that all the planets except the earth went around the sun and the sun circled the earth. He was the last of the great astronomers to hold that the earth was the center of the universe. Johannes Kepler - brahes assistant - mars moved in a ellipse LAWS - planets move in elliptical orbits with the sun at one focus of the ellipse - the orbital speed of a planet varies so that a line joining the sun and the planet will sweep over equal areas in equal time intervals - the amount of time a planet takes to orbit the sun, P, is related to its orbits size,a. Newton Laws - A body continues in state of rest or in uniform motion in a straight line at a contrant speed, unless made to change that state by forces acting on it ( an object in motion stays in motion, an object at rest stays at rest. - F- Ma - Equal and opposite reactions (when x exerts force on y , y exerts force on x so they both accelerate) Gravity- every mass exerts a force of attraction on every other mass. (Fg= G(Mxm/d2) Orbital Velocity- the speed needed to maintain a (generally) circular orbit.

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Modified Keplers 3 rd law Ma+ Mb= a3AU/ p2yr Escape Velocity- the minimum speed an object without force needs to attain in order to "escape" from gravity, i.e., so that gravity will never manage to pull it back Nature of electromagnetic Radiation Frequency- the number of times per second that a wave vibrates ( f=v/ λ ) Wavelength- the distance between wave crests. They determine the color of visible light and are denoted by lambda ( λ ). λ =P(plancs constant)/p(momentum of particle) The Doppler Effect
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Astro Study Guide - Astro Study Guide Scientific Method The...

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