PPT-Stars, Galaxies, and the Universe

Chapter 21 How does distance affect an image Telescope device that makes an object in the sky appear closer Revolutionized astronomy study of space allowed them to see objects in space for first time. Homogeneous and uniform cosmic expansion . Hubble constant determines scale factor . Hubble diagram was based on a limited distance scale calibrated by Cepheid variable stars in relatively nearby galaxies. Recap. Canvas homework: due on Wednesday. Lab this week: Galaxy Morphology. Campus Observatory. Milky Way galaxy. Stars: . brightnesses. , masses, sizes, compositions, evolution. Interstellar matter: gas, dust. Galaxy Morphology and Environment. Main relation – . E’s more common in clusters than field. f(E. ) = fraction of ellipticals . f(Sp. ) = fraction of spirals. regular, symmetric cluster – . f(E. 23. vs. .. 1. First spiral nebula found in 1845 by the Earl of . Rosse. . Speculated it was beyond our Galaxy.. 1920 - "Great Debate" between Shapley and Curtis on whether spiral nebulae were galaxies beyond our own. Settled in 1924 when Edwin . Ms. Cordaro . SMHS . Earth Science. Review/Warm up – Write this in your journal. (Do not fill in the blanks yet!!). A light year = How far _ _ _ _ _ travels in _ _ _ year.. The electromagnetic spectrum is made up of different size _ _ _ _ _ that produce _ _ _ _ _ _ in the form of radiation.. Extraterrestrials. CELESTIAL BODIES. Astronomy that influence people’s lives and behavior. Astronomy – study of the night sky(planets, galaxies, stars, and other celestial bodies). UNIVERSE – it is everything that exists. Atoms to Astronomy. 2. Special theory of Relativity. It is a basic property of Nature that:. Velocity of Light in vacuum is constant.. All inertial frames are identical so if two objects are moving with a constant velocity, it is impossible to do any test which allows to measure the velocities in absolute manner.. . Loners. Interactions were once . believed to be unimportant . and rare.. Galaxies were thought to . be . isolated loners. , well . separated from one . another . a. nd scarcely interacting.. Au Contraire!. Lecture 2; . April 9 2013. Previously.. On Astro-2. The goal of cosmology is to understand how the universe formed and evolved.. How can we build a theory of the universe valid at all times in every place? . Let’s look back at the rotational velocity equation:. v = (M. interior. G/r). 0.5. The rotational velocity is constant at big r values.. What must we conclude?. The mass interior to the orbit is still increasing. Even after the radius r has gone beyond the last of the stars. It must be increasing in order to hold v constant.. The universe is a big place, perhaps the biggest. . –Kurt Vonnegut. Cosmology. Cosmology is the study of the nature of the universe, how the universe began and how it will end, if it does. There is religious cosmology, and scientific cosmology. constellations. a. Ancient cultures used . mythology. or everyday items to name constellations. 2. Modern astronomy studies . 88 . constellations. 3. Some constellations are not . visible. all year because Earth revolves around the Sun. The universe is a big place, perhaps the biggest. . –Kurt Vonnegut. Cosmology. Cosmology is the study of the nature of the universe, how the universe began and how it will end, if it does. There is religious cosmology, and scientific cosmology. Laura . Magrini. INAF- . Osservatorio. . Astrofisico. di . Arcetri. In Our Galaxy. Open clusters (disc population): . Many (~2200 known clusters). . even more new candidates in the inner disc from infrared surveys .