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Final Exam Review Questions and Answers

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Natural Science
NATS 1745
Robin Metcalfe

NATS1745 60 History of AstronomyFinal Exam Review Chapter 8 1 What was William Herschel looking for when he discovered UranusHe was cataloguing stars to aid the search for stellar parallax What made Herschel particularly suited for discovering planetsHe was an amateur astronomer who built the largest telescope of his time In what 2 ways did Uranus reveal itself to Herschel as a planeti He observed a starlike object which increased in size when he increased his telescope magnification ii Shortly after he observed its motion relative to the stars What is it about Uranus orbit that caused it to be considered a planet instead of a cometFurther investigation revealed its nearcircular orbit 84 years orbital periods Comets have an elliptical orbit What is the origin of Uranus nameGreek god of the sky father of Saturn grandfather of Jupiter 2 What did Kepler believe existed between the large space between Mars and JupiterWhen Kepler observed the large gap between Mars and Jupiter he proposed it contains an undiscovered planet Explain why Bodes Law supported this ideaBodes Law the orbital radii of the 6 known planets follow a sequence of numbers Bodes sequences were very close to the actual distances The number at 28AU at no corresponding planet which falls within that gap which suggested that there might be an undiscovered planet 3 What is the name of the object found in 1801 between Mars and JupiterCeres What was this object finally classified as and whyDowngraded from a planet to asteroid when it was found to be smaller than the Moon asteroid is Greek for starlike What is this object a part ofAsteroid belt This object is a part of the circular belt that contains hundreds of asteroids discovered between Mars and Jupiter 4What causedAdams and Leverrier to suspect the existence of a planet beyond UranusDeviations were detected in the orbit of Uranus When this planet was found what was it named and why This planet was named Neptune Roman Sea God owing to its bluish colourChapter 8 15 How were the masses of Uranus and Neptune 1st measuredrdKeplers 3 Law was applied to get the mass of whatever the moon was orbiting around How do their masses compare with the other planetsUranuss mass is 15x Earth and Neptunes mass is 17x Earths they are not nearly as massive as Jupiter or Saturn Based on the masses and sizes what do we know about their densities and compositionsThey are light like Jupiter and Saturn and are low density and therefore gaseous Gas GiantsWe call them Ice Giants because a lot of their material is frozen Their composition has a small rocky core the rest of the planet is hydrogen gas and frozen based hydrogen based molecules6 What is todays theory for why all the planets in our solar system orbit the Sun in the same direction and in roughly the same planeCurrent theory after the Sun was born from a spinning collapsing gas cloud the remaining gaseous and rocky particles in the Suns spinning circumstellar disk coalesced into planets What is the observational evidence for this theoryThe proof disks of matter have been found around newborn stars in starforming nebulae 7 What is todays theory for the asteroid beltThe asteroid belt is likely the leftover debris from the Suns circumstellar disk that couldnt coalesce into a planet due to the opposing gravitational pulls of the Sun and nearby giant Jupiter What about planetary ringsPlanetary rings are likely the leftover debris from protoplantary disk around a planet rather than a disk around a star disks which couldnt coalesce into a moon 8 What 3 attributes are unique to the 4 planets beyond MarsThe 4 planets beyond Mars are all gas giants have numerous moons and all have rings What is the current explanation for thisThe reasons The outer circumstellar disk contained more material allowing the outer planets to collect more mass and to attract more debris into orbit as moons and rings9 Which planets are the terrestrial planets The inner most planets Mercury Venus Earth and Mars What is the current explanation for their lack of gas stThe planets solid cores were likely the 1 to form Since the outer planets grew faster they had more gravity to draw in the gas particles leaving the inner planets with much less gas 10 What is the current theory for the origin of Mars two moons The theory that they were once asteroids and they got pulled from the asteroid belt or they collided with something and got thrown outside of the asteroid belt and then head towards Mars and got caught in Mars gravity What is the evidence to support this theory Chapter 8 2 Both look like asteroids and 1 is retrograde they dont spin counterclockwise11 Why is it unusual for Earth to have such a large moon Because Earth is an inner planet and it was formed in the inner part of our solar system where there is not enough matter to make a moon What is the current theory for the origin of Earths moon The large size and composition of Earths 1 moon suggests that it came from a large Earth impact 12 What belief about Mars was popularized by Percival Lowell and why Lowell popularized the idea of intelligent life on Mars because he was an American businessman and astronomer particularly interested in finding life on other planets Was he right His theories were rejected after close up observations of Mars 13 Why was there suspected to be a planet beyondNeptune An initial understatement of Neptunes mass led to the theory that an additional planet is disturbing Uranus orbit 14 WhenLowells predicted planet was finally detected what was it named who named it and why did she choose this name The planet was named Pluto Greek god of the Underworld by a young girl from England a dark and gloomy planet 15 Why did the discovery of Pluto turn out to be a coincidenceThe discovery of Charon largest of Plutos 3 moons revealed Plutos mass 002 x Earth too small to disturb Uranus Plutos discovery was therefore a coincidence 16 The discovery of what kind of objects motivated the IAU to define the conditions for being a planet Hundreds of Kiuper Belt Objects KBOs have been discovered some larger than Pluto Where are these objectsThese objects are a disk of icy debris around the planets left over from the solar systems birth beyond the orbit of Neptune sometimes they are called transNeptunal objectWhat was the significance of the object now known as Eris Eris was found to be more massive than Pluto it was first thought that Eris was thnamed to be a 10 planet but more of these Pluto like objects were found in the Kiuper Belt it motivated our definition of a planet 17 What are the IAUs planet conditions i It must be in solar orbit excludes moons ii It must be a sphere by its own gravity excludes comets and some asteroids iii It must have cleared the debris around its orbit excludes all asteroids and KBOs Which conditions does Pluto fail3 because Pluto is in the Kuiper belt and it is full of debris and it is part of that debris What conditions do comets fail2 generally not spheres and 3 they come from a cloud of debris What conditions do asteroids fail Chapter 8 3
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