Astro 006 Unit 1 Complete!

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Astronomy and Astrophysics

Astronomy 006 – Unit 1 January 13, 2014 • Star:Aglowing ball of hot dense gas that generates its own energy • Planet: a smaller body orbiting a star • Galaxy: a huge collection of stars, all held together by their mutual gravity • Universe: Everything – all matter, energy, and time Syllabus online at angel website Homework #1 listed on angel Bring Workbook everyday starting Wednesday 2 recommended textbooks January 15, 2014 Big Ideas – Core concepts • Science • Light • Look-back Time • Gravity • Star Stuff • The Universe is Dynamic • Space is Big 3.1x10 seconds in one year Look-back Time: because of the finite speed of light, we see objects as they were in the past o The farther away we look in distance, the farther/longer back we look in time o Allows/forces us to study the history of the universe Light year: is a measurement of distance • How far is a light year? o Known: Speed = c (speed of light) o Time = 1 year = 3.1 x 10 seconds • Distance = speed x time ONLY when speed is constant Distance = 3 x 10 km/sec x 3.1 x 10 sec = 9.5 x 10 km January 17, 2014 Constellations:Arbitrary patterns of stars that have a historical reference to mythological figures • Stars are nowhere near each other in space; just appear to be from our perspective Astronomy 006 – Unit 1 January 24, 2014 What is the relationship between the altitude angle that the North Star appears in the sky and the observer’s latitude angle on earth? • Direct relationship – as one increases, the other does too What is Science? • On going process of: o Making testable predictions o Gathering evidence o Testing ideas repeatedly with experiments • Is NOT: o Alist of facts, equations, and numbers Astrology (not the same asAstronomy): • The belief that the positions of the planets and Sun as seen from Earth determine human events o Astronomy = Science o Astrology = Bull shit Astronauts in the space station feel weightless because: • They are falling January 27, 2014 Why doAstronauts in space feel weightless? – Question will be on exam! The Sun: Our Star • Rotate: turning around an axis in itself (spinning) • Revolve: turning around an axis outside of its self (orbiting) o The Sun both rotates (in 30 days) and revolves • Why does the Sun Shine? o Sun shines because its hot; hot things glow o Has an energy source from nuclear fusion (making it hot) • Nuclear Fusion (nuclei of atoms, combining) o Combining lighter elements (nuclei of atoms) into heavier ones o In the Sun, and all normal stars, HHe (hydrogen to helium) o This is how normal stars produce energy in their cores o Nuclear fusion releasesALOT of energy because of E=mc 2  E = energy released; m = tiny bit of mass is lost; c = speed of light • Key Features of the Sun’s anatomy Astronomy 006 – Unit 1 o The sun is hottest at the core because that’s where it is hottest o Although no hard surface, we see a distinct edge (photosphere) • How long will the Sun live? o Rate Problems: amount = rate x time (a=rt) o Amount=6 pizza; rate=2 pizza/day; time=? • The sun is in gravitational equilibrium: o Pressure and gravity are balanced (gravity goes to core; pressure leaves core) • Sunspots are each as big as the earth January 29, 2014 • Light is important because it’s the only source of information we have about most astronomical objects o 2 correct ways to describe light:  Particles (photons) – no mass (only difference from atoms)  Waves (electromagnetic waves) • Properties of waves: o Wavelength - λ - measured in meters, km, cm, nm o Frequency - f - measured in the # per unit of time (Hertz Hz) (Hz = 1/sec) o Speed - S (always = C) – measured in m/sec, km/sec, cm/sec • The wave equation λ x f = c o Wavelength and Frequency are inversely proportional to each other • Radio wav
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