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Chapter 10 - Exam Review Questions.docx

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Natural Science
NATS 1745
Robin Metcalfe

NATS1745 60 History of Astronomy 201112Chapter 10 Exam Review1 What is the Island Universe theorya Immanuel Kant said that elliptical nebulae seen in the sky are actually disk shaped star systems independent galaxies Our galaxy is one of the many galaxies that exist They are like separate island2 Why did the Ancient Greeks use the word galaxy to describe the bright strip of light across the sky What do we call this strip of light today What part of our galaxy does this strip representa Galaxy means Milk in Greek it was names by the Greeks due to its Milky appearanceb The light represents the stars in the disk of our galaxy3 What did William Caroline and John Herschel produce together What was Herschel attempting to prove from this research Why was he not able to prove thisa Produced a catalogue of over 5000 nebulaeb They attempted to identify whether nebulae are distance star systems or nearby glowing gas cloudsc There were varieties of nebulae some looked like galaxies and some looked like gas clouds thus he couldnt conclude what they are composition4 What did Herschels map of the visible stars reveal about the shape of our galaxya His map revealed our diskshaped star system5 What did Lord Rosse discover when he looked at the ellipticalshaped nebulae through his Leviathan telescopea It showed that many elliptical nebulae are spiral nebulae6 What is a variable star What characterizes the Cepheid variables Explain briefly why Cepheids pulsatea Variable stars are stars whose brightness are increasing and decreasing at regular time intervalsb Cepheids are a type variable star that are very luminous and also pulsate rapidly at intervals of days to weeksc A Cepheid has highly dense surface due to having many tightly packed atoms Its photons push the stars surface outwards which temporarily expands the stars surface making space for the photons to escape Then it shrinks again making the core dense7 What are the SMC and LMC What did Henrietta Leavitt discover when she observed Cepheids in the SMC Why was this discovery so valuable Who used her discovery to determine the boundaries of our galaxya SMC is the Small Magellanic Cloud and LMC is the Large Magellanic Clouds they are galaxiesb The brighter the Cepheid the longer its periodc Discovering Cepheid period was valuable because it gives way its luminosity and therefore its distance which is the distance to its star systemsd Harlow Shapley8 What are the 3 components of our galaxy according to Shapleys model Where is the Sun located in this model Where is the Galaxys centre In what 2 ways is this model incorrecta There is a spiral disk of stars a bulge of stars and halo of star cluster and nebulaeb The sun is located in the outskirts of the diskc The centre is in Sagittariusd He was wrong about where the spiral resided and the size of the disk he estimated it was three times bigger
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