|- Hubble Diagram|
|- Spectral Types|
|- H-R Diagram|
|- Sky Surveys|
|Games and Contests|
|Links to Others|
|Hubble Tuning Fork|
|- Using Clusters|
A good way to study the properties of many galaxies is by looking at a galaxy cluster. There are many galaxy clusters in the SDSS data, which may contain hundreds or even thousands of galaxies.
The picture at the right shows a famous cluster called Abell 2255. The cluster is named after George Abell, an American astronomer who published a catalog of galaxy clusters in 1958. In this project, you will study the galaxies that make up Abell 2255.
If you have completed the Color project, you are now ready to use Abell 2255 to learn about the nature of galaxies.
Using Galaxy Clusters in Astronomy
In Exercise 4, you looked at only a few galaxies. To draw convincing conclusions about galaxies, you need to examine hundreds or thousands of galaxies - far more than you could look up individually. Therefore, in the next exercise, you will use a search tool to automatically look up information on all the galaxies in Abell 2255.
Your teacher may tell you which one to use, or you could pick one yourself. Click one of the links below to learn how to use the tool of your choice. A new page will open in this window. When you are done, you will return to this page to make and analyze your color-color diagram.
Use the Radial Search tool and Excel
Use the SQL Search tool
SDSS astronomers recently analyzed over 147,000 galaxies and created a diagram similar to the one you made in Exercise 5. If you are interested in some challenging reading, you can download the paper they published here (to see the paper as a .pdf file, click Other Formats, then Download PDF).