Galactic Inquiry




Дата канвертавання24.04.2016
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Galactic Inquiry


Overview

In this activity, students view NASA images of galaxies and develop a galaxy classification scheme.  Students then compare and contrast their classification scheme to Edwin Hubble's scheme. 




Directions


Part I: Developing a Classification Scheme

Although Immanual Kant first advanced the idea of "island universes" to explain the observed compact clouds during the eighteenth century, it wasn’t until this century that astronomers began to develop an understanding of the nature of galaxies.  Your instructor will provide you with galaxy photographs. Your first task is to sort the galaxies by creating and applying a classification scheme based on appearance.  Complete the table below. 


 

 

Galaxy ID Numbers 

Defining Characteristics (provide enough detail so that anyone could use your scheme)

Category I

 


Category II

 



Category III



 


Category IV

 

 
 


 
 

Part II: Applying Hubble’s Classification Scheme

After you have completed Table 1, ask your teacher for a copy of Edwin Hubble’s classification scheme, which was developed in the 1920’s.  Complete the following table using his scheme. 


 

Hubble’s Categories 

Galaxy ID Numbers 

Defining Characteristics (describe the characteristics used by Hubble)

 

 
 

 

 
 


 
 

 

 
 

 

 
 


 
 

 

 
 

 

 
 


 
 

 

 
 

 

 
 


 
 



Reflection Questions to Answer

Question 1: Unless there is an underlying model, classification systems are completely arbitrary as long as the defining characteristics are clear to everyone.  Which of the two systems, yours or Hubble’s, does your group prefer?  Why?

Question 2: Hubble viewed the tuning fork diagram as representing an evolutionary sequence for galaxies.  Using the tuning fork diagram, propose an evolutionary sequence for galaxies. 

Question 3: Astronomers now realize that the tuning fork diagram does not represent an evolutionary sequence.  Does this mean that Hubble’s scheme is useless? Explain. 

Answer Key

Scientific Name

Classification

Name

M32

E2

M101

Sc

Pinwheel Galaxy

M65

Sa

One of the Leo Triplets

M109

SBc

Vacuum Cleaner Galaxy

M82

Irregular

Cigar Galaxy

M51

Sc

Whirlpool (colliding)

Large magellanic cloud

Irregular

Arp 252 (may not want to use this one)

(Peculiar)

NGC 4565

Sb

M81

Sb

Bode’s Galaxy

M87

E1

Smoking Gun

M104

Sa

Sombrero Galaxy

NGC 2146 (man not want to use this one)

(Peculiar)

NGC 1365

SBc

Has huge black hole

NGC 4650a

SO

NGC 6946

Sc

Leo 1

Dwarf elliptical

NGC 253

Sc

Silver Coin Galaxy

M59

Elliptical

NGC 1073

SBc

 





Galaxy classification 2007http://btc.montana.edu/ceres/html/Galaxy/galstudentact.html


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