ISP Exam 1 - ISP Exam 1 18:21 The Most distant Galaxies and...

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Unformatted text preview: ISP Exam 1 18:21 The Most distant Galaxies and Quasars: 13 billion light years away o Light took 13 billion years to reach us o We see them as they were 13 billion years ago We can trace the history of galaxies being assembled from smaller units What is the Universe Made of? Normal Matter o Atoms made of protons, neutrons, electrons. o Interact through gravity, light Dark Matter Interacts via gravity, but not with light o Gravitational lensing shows that 85% of all matter is DARK MATTER o What is it? Nobody knows. An Expanding Universe Gravity should slow expansion rate BUT it is measured to be speeding up! DARK ENERGY What is the Universe made of? 4% Normal Matter (this is the only part we see) 23% Dark Matter 73% Dark Energy o (we infer these are there, but we dont know what they are) Units of Astronomy Scientific notation o 100,000,000,000.= 10^11 o 0.001= 10^-3 o 200,000,000,000= 2X10^11 o 0.003 = 3x10^-3 Metric units o Diameter of Earth: 1.3x10^4 =13,000km (8,000 miles) o Circumference of Earth: 4x10^4 =4E4= 40,000km (25,000 miles) Astronomical unit (as or AU): radius of Earths orbit o 1.5x10^8 km (93 million miles) Light year (ly): o Distance light travels in 1 year = 9.5x10^12 km (5.9X10^12 miles) How does the Earth fit into the cosmos? Inside the solar system Which is inside the Milky Way Galaxy Inside the Local Group Inside the Local supercluster The universe Ancient Greeks had remarkable successes: Knew Earth is round Measured earths diameter Precession: 26,000 year wobble of Earths axis But one major error: o They thought that the Earth was at the center Retrograde Motion and Ptolemys Epicycles Trying to place Earth at the center Using only circular motions and constant velocities Led to very complicated system 1543: Copernicus proposed sun is at center Assumed each planet on circular orbit about sun Retrograde Motion just due to planets passing each other in their orbits Johannes Kepler (1571-1603) Analyzed data after Tycho died Discovered 3 laws that together describe the motions of all the planets Keplers 3 Laws PAGE 67-68 Each planet moves around orbit in ellipse, with sun at one focus The straight line joining the planet and the sun sweeps out equl areas of space in equal amounts of time P^2= a^3 o P = period of orbit in years o A= semi-major axis of orbit, in au Early 1600s: Galileo First to use telescope to look at night time sky o Smaller details o Fainter objects The Scientific Approach: o The explanation must fit the observed facts...
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This note was uploaded on 05/17/2011 for the course ISP 205 taught by Professor Donahue during the Spring '08 term at Michigan State University.

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ISP Exam 1 - ISP Exam 1 18:21 The Most distant Galaxies and...

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