Exam Review AST 1002-Section 3
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This 9 page Study Guide was uploaded by Alexandra Wendling on Monday September 19, 2016. The Study Guide belongs to AST 1002-Section 3 at Florida State University taught by Vladimir Dobrosavljevic in Fall 2016. Since its upload, it has received 9 views. For similar materials see Planets, Stars and Galaxies in Science at Florida State University.
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Date Created: 09/19/16
Lecture 9/7/2016 Cosmological Principle 1. Law of nature is same everywhere Observation Tools: powers of ten (our planet is 10,000 km) 1 mile=1.6 km 1 km= 1000 meters Proxima Centauri 1. closest star to us (next to the sun) Proxima means close and centauri means constellation (shaped like cursive L) ((alpha centauri) Light year One light year = 10^13 km Light year covered by light in 1 year Distance to nearby stars is 10 light year Night sky We can’t see the stars during the day because of the ozone layer and sun (the sky is blue because of the air) During the night time, we can see 1. Stars 2. Planets 3. International Space Station (ISS) 4. Comets Map of the sky “Cellestial Sphere” Lecture 9/7/2016 Celestial sphere apparent sphere of the sky Celestial equator projections of earth’s equator Celestial poles axis of rotation Ecliptic annual path of the sun as projected onto the celestial sphere Motions in the sky 1. Stars 2. Planets 3. Comets 4. Moon Constellation groups of stars that appear close to each other Stars move from east to west The north star never moves Altitude of Polaris is always the same as what you’re latitude is. (if you wanna look for polaris just measure out degrees ((a fist= 10 degrees and finger is one degree))) Zodiac The sun visits all 12 zodiac area (aka horoscopes) Seasons are due to tilt of earth’s axis Equator is 12 hours of day/night Summer solstice longest day of the year (June 21) Winter solstice longest night (december 25) Vernal equinox both exact 12 hours of day and night Autumnal equinox Spins quickly but axis “precession” Brightest star Sirius Lecture 9/7/2016 Eclipses vs Phases of Moon Solar eclipse gives a new moon Lunar eclipse gives a full moon Lunar eclipse only happen once or twice a year due to a 5 degree tilt of the moon’s orbit Ancient Astronomy Magellan traveled the world by boat and people figured out the earth is round because things disappear below the horizon. Erastohenes discovered how big the earth was. He lived in Alexandria in 200 BC. Stars rise in the east and set in the west Planets from west to east Crystal sphere shows what layers the planets are in Aristotle stated that the earth is Geocentric to the crystals in space. Ptolemy used Aristotle’s idea and realized that planets don’t move in a circle, rather a Retrograde motion. Ptolemy thought the Mars was moving on an epicycle (a little circle) The deferent is the big circle around earth. But what is at the center of the small circle (epicycle)? NOTHING! Copernicus (1500s) Disovered that all planets go around the sun and that things look like theyre going backwards when u pass them yourself. Heliocentric means the sun is in the center of the system (Ptolemy and Aristotle is wrong) Galileo used the telescope Phases of venus: Either looks like a full moon or a crescent moon Lecture 9/7/2016 Lecture 4 The Secret Motion of Planets Kepler discovered and described how planets move, how they move Newton why they move, equations behind it KEPLER Student of a Prince (Tycho de Brache) He observed stars for 20 years Kepler’s II Law: equal areas “roller coaster law” (far from the sun, it’s slower. Closer to the sun, the comet is faster) Orbital period vs size: Distance in “astronomical units” (1 AV= distance earthsun) Keplers III Law: P^2 = a^3 The orbits of all planets (comets, asteroids, moons) are all ellipsis. Eccentricity is deviation from the circle Mercury has a bigger eccentricity Comets have a very large eccentricity In the middle of the ellipsis it’s slower, and the outside is faster NEWTON What is the force equation? If we know the force, we can describe the motion Law of universal gravitation: F = Force applied to the object m= mass of the object a = resulting acceleration (rate of change of speed) His three laws: Lecture 9/7/2016 A body stays at rest or in uniform motion unless there is an external force (Law of Inertia) A body’s motion (velocity) is proportional to the force acting on it (F= m * a) When a body exerts a force on a second body , the second body must exert an equal force 11 3 2 G=6.672x10 m /kg/s 2. Earth would not have seasons if its equatorial plane were perpendicular to its orbital plane. its axis of rotation were perpendicular to its equatorial plane. the observer's vertical axis (zenith) were perpendicular to Earth's orbital plane. its axis of rotation were perpendicular to its orbital plane. 3. The Arctic Circle is defined as a line on Earth where the Sun always shines, winter or summer. can be seen for 24 hours on at least one day of the year. is always 23.5° or more above or below the horizon. never shines at any time of the year. 4. When the Sun is at one of the equinoxes, the day is longer than the night in one hemisphere of Earth and shorter in the Lecture 9/7/2016 other hemisphere. day and night are of equal length only for people on the equator. people on the equator have perpetual daylight. day and night are of equal length everywhere on Earth. 5. The person who introduced the leap year into our calendar was Sir Isaac Newton. Pope Gregory XIII. Julius Caesar. Ptolemy. 6. Because of precession, how long will it be before the spin axis of Earth points toward the present pole star again? at least 1 million years 13,000 years 26,000 years 9 years 7. Which of the following is the correct sequence of appearances of Moon phases in the sky? waxing crescent, first quarter, waxing gibbous, full Moon new Moon, full Moon, waxing crescent, waning crescent full Moon, waxing gibbous, third quarter, waning crescent new Moon, waning crescent, first quarter, full Moon Lecture 9/7/2016 8. The full Moon always occurs on the first of the month. when the Moon is at right angles to the direction of the Sun. when the Moon is closer to the Sun than Earth is. when the Moon is farther from the Sun than Earth is. 9. The full Moon can be on the horizon only at sunrise or sunset. only at midnight. at any time, day or night. only at midday. 10. The phase of the Moon at the time of solar eclipse is full. can be any phase: new, quarter, or full. is new. is third quarter. 11. Eclipses of the Moon can occur only in the spring and fall, when the Sun is on the ecliptic plane. at new Moon. Lecture 9/7/2016 in June and December, when the Sun is near the solstices. at full Moon. 12. The direction of retrograde motion for a planet as seen by an observer on Earth is west to east relative to the background stars. east to west relative to the background stars. east to west relative to objects on the person's horizon. west to east relative to objects on the person's horizon. 13. Ptolemy's model for the solar system was Earthcentered, with the Sun, the Moon, and the planets moving in ellipses in the sky. Suncentered, with elliptical planetary orbits. Suncentered, with the planets moving in circles around it. Earthcentered, with planetary orbits composed of deferents and epicycles. 14. The epicycle, in the Greek planetary model, is the circle centered on Earth about which the center of the smaller circular motion moves. offcenter point in the planetary system occupied by Earth. focus of the ellipse that is the orbit of the planet around Earth. small circle through which the planet moves as the center of this circle orbits Earth. Lecture 9/7/2016
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