Sloan Digital Sky Survey SkyServer DR15

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Classifying Galaxies

Pretend that you are an astronomer working shortly after Edwin Hubble made his startling discovery. Now that you know the "nebulae" are actually other galaxies like our own, you must come up with a way to classify the galaxies.

Exercise 1: Look at the following galaxies. Divide them into groups based on features they have in common. There is no set number of groups.

Click one of the links in the table below to use the Get Fields tool to look up each galaxy. You will see a picture of the field the galaxy is in. Because galaxies tend to cluster together, some of the fields have more than one large and interesting galaxy. In all the other frames, the largest galaxy should be obvious. When you click another link, the new field will appear in the same window. You may want to print the fields out, so you can compare the galaxies side-by-side.

Use this SkyServer workbook to keep track of your groups.

 Run Camcol Field 752 1 244 2662 4 243 752 1 331 1737 6 11 756 4 198 2738 2 196 752 1 432 3325 3 319 3325 2 216 3325 2 215 (just left of center) 3325 3 230 (2 galaxies) 2738 3 122 (2 nice galaxies) 3325 3 352 3325 1 356 3325 1 359

Now, find another group and partner up with them to compare your results.

 Question 1: Do you have the same number of galaxy classes? If not, what distinctions did one group draw that the other did not?

 Question 2: What do your classification systems have in common? What makes them different?

 Question 3: Try to combine the best features of each classification system. Repeat Exercise 1 with your new system.