ASTR 151 1nd EditionExam # 1 Study Guide Lectures: 1 – 2, 5, and 61.Lecture 1 (Chapter 1) a. Scientific Theory must have beauty, simplicity, and comprehensivenessi. Scientific Theories can be proven wrong but can`t be proven right with 100% certainlyb. Scientifics Law does not explain why something works, it merely states that something works with no evidence to back up the claimc. Scientific Method is a constant cycle d. The universe is a totality of all space, time, and matter measured in light-yearse. Observation leads to theory, theory is best proven by observation: The Science Circle of Lifef. Ancient Romans grouped the stars together to form Constellations; groupings that have meaning and purposeg. Astronomers use the celestial sphere to gain two dimensional coordinates, basedon latitude and longitudinal lines of the earthh. Angular Measure is used with a base of 10. It depends on the size of the star itself2.Lecture 2 (Chapter 1)a. Solar day is a daily cycle in diurnal motionb. Sidereal Day is stars that aren`t always in the same place after one earth rotationc. Earth`s orbit is ecliptic, where the path is tilted 23.5 degrees to celestial equatord. Summer solstice northern point of the path closest to the sun. Winter Solstice Southern point of path closest to the sune. Day length and sunlight makes the seasonsf. Precession – a complete (26,000years) rotation of earth`s axisg. Synodic Month is a complete (29.5days) rotation for the moon`s cycleh. Moon`s phases are made by different amounts of sunlit portions that are visible from Earthi. Sidereal Month is two days shorter than synodic month; the moons rotation around the earth.j. Moon`s phases: Waxing crescent, 3rd quarter, Waning Gibbons, Full Moon, Waxing Gibbons, 1st quarter, Waxing Crescent, and New Moonk. Lunar eclipses occurs when the earth is between the Moon and Sun, light from the earth is reflected from the earthl. Solar eclipses occur when the moon is between the sun and the earthm. Solar eclipses partial occurs when part of the sun is blockedn. Solar eclipses annular occurs when the moon is too far from earth o. To measure earth`s radius, use measuring angle and distance between two cities3.Lecture 3 (Chapter 2)a. Astronomers observe the Sun, Moon, Stars, and five planets; Mercury, Venus, Mars, Jupiter and Saturnb. Planets seemed to Undergo retrograde motion (orbits in a circular motion and then randomly orbits backwards)c. Inferior planets are never too far from the Sun, Superior planets are unattached to the sun`s gravity.d. Geometric Model made by Claudius Ptolemy; put earth in the center and needed80 circles as orbit modelse. Copernicus retained perfect circles as orbit models in his model: All planets revolved around the sunf. Aristarchus of Samos believed the sun was the center of our universeg. Heliocentric Model: sun at the center with only the moon orbiting earthh. Telescopes were built around 1600si. Galileo built his own telescope which later blinded him, published Sidereus Nuncius and deemed a heretic4.Lecture 4 (Chapter 2)a. Tycho Brahe last of the naked eye astronomer; observed comets and new starsi. Made the Tychonic system merge between Ptolemic and Copernican models: Earth doesn’t move but planets orbit the sunb. Johannes Kepler created the laws of motion (Kepler`s Laws)c. Planetary Motion Lawsi. Planetary orbits are ellipses with the Sun in the Centerii. Imaginary line connecting Sun and planet sweeps out equal areas in equaltimesiii. Square of period of Planet`s orbital motion is proportional to cube of semi major axisd. Solar System Dimensions i. Astronomical units measure the distance between the earth and sun (AU)5.Lecture 5 (Chapter 2)a. Newton`s 3 Law i. Explains how objects interact with world and with each other: Vector=Direction and Magnitudeii. Newton`s Laws: 1. An object at rest tends to stay at rest2. F=m*a3. For every action, there is a reactionb. Newton`s Mechanicsi. G = Gravitational force is weight aimed towards the center of the massii. Kepler`s laws are consequence of newton`s laws- first law should be modifiediii. The force keeping the planets in orbit around the Sun is the gravitational force due to the masses of the planet and sun6.Lecture 6 (Chapter 5)a. Optical Telescopes – collects visible light and focuses it at one pointi. Visible light – small part of the electromagnetic spectrum energyii. Reflective1. Reflecting mirror depends on the size of the lens2. Large lens work best but they are very heavya. Types four:i. Primeii. Neurtonianiii. Cassegrainiv. Nasmyth/coud`e focusiii. Refractive1. Change in direction with a transmission medium2. Lenses depend on energy/ frequency/ and wavelengths of light3. Chromatic aberrationiv. Sizes1. Larger mirrors can gather more information2. Angular Resolution is the smallest distance between two resolvableobjects and measured in arc secondsv. Images detectors1. Image acquisition is subdivided be 2demisional array of pixels2. Computers analyze and process and analyze imagesvi. Atmospheric blurring – called “seeing” point sources out as speckle platters1. Long exposure images7.Lecture 7 (Chapter 5)a. Radio Astronomyi. Adaptive Optics – real time changes in atmosphereii. Telescopes – Prime focus type, resolution still depends on wavelengthiii. Advantages Less sensitive to imperfections due to longer wavelength and observes for a full 24 hoursb. Interferometry – amount of interference depends on the direction of signali. Can be done in the light but difficult to absorbii. Electro-magnetic signals – combines information from widely spread plates are super imposed to get information about the waves1. Construct in phase – sound waves move in unison2. Destruct out phase – sound waves move out of unisonc. Space-Base Astronomy1. Infrared Telescope - Produces images where visible radiation is blockedii. Gamma Rays1. Can`t be focused at all so images are blurry2. X-rays will reflect if it happens to come in fairly shallowd. Full-Spectrum Coveragei. James Webb – his telescope looks for light dating to the Big Bang of the universe, also can see infraredii. Redshift – wavelength changes based on motion away and towardobserver as well as speediii. Cosmo Redeshift – shows the universe still expanding1. Depends on how quickly and object moves8.Lecture 8 (Chapter 6)a. Eight planets were added to the official recordsb. More than 800 extra solar planets have been foundc. Density = m/v: Radius is found through
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