Astronomy 201: Cosmology Fall 2009 Prof. Bechtold NAME: The Galaxy Zoo Project 200 points Due: Nov. 23, 2010, in class Professional astronomers often have to search through enormous quantities of data in order to find an interesting result. Usually, the approach is to write a computer program to search the data automatically. But there are some types of analyses that are difficult to train a computer to do. Human brains are very good at seeing patterns in complex images, and it turns out that it s sometimes hard to write a computer program to do as good a job at pattern recognition as a human. For example, in medical imaging, it is now standard to use digital cameras to take mammograms and to do other types of cancer screening, and computer programs are used to flag suspicious structures in the images, but in the end, the images are looked at by a pathologist, because there is no substitute for a trained eye. In this homework, you are going to participate in an interesting on- line project which uses the public to classify galaxies as spirals, ellipticals, etc.. This project is called The Galaxy Zoo. The Galaxy Zoo is based on images taken with the Sloan Digital Sky Survey telescope in New Mexico. This telescope has taken millions of images and millions of spectra of stars, galaxies and quasars. The data is all on- line, and professional astronomers have been data mining the Sloan Survey for several years. They have found all sorts of interesting results. The Galaxy Zoo project is basically interested in producing a catalog of the galaxy type for millions of galaxies in the Sloan Digital Sky Survey. It trains you to classify galaxies in terms a few simple rules, gives you some example galaxies to classify, and then lets you classify as many galaxies as you want. Your classifications are added to the millions that have already been done by others. Each galaxy is classified by many different people, so if you enter something wrong they will be able to flag your classification as suspect i.e. if you say some galaxy is a spiral and a hundred other people say its an elliptical, they will throw your classification out. So there is no real right or wrong answer. The point of this homework assignment is to familiarize you with a citizen astronomy project, and let you look at a number of real galaxies. In classes and textbooks, we tend to show pictures of beautiful galaxies, but real galaxies are a lot messier. And you can tell your friends and family that you got to do real astronomical research as part of this class! By completing
this assignment, you will be contributing to a state- of- the- art astronomical research project. The first citizen astronomy project was SETI at Home which is still going on. This is a project where you download a program to your computer and analyze radio signals from radio telescopes to look for communications from extra- terrestrial civilizations. See their web page: http://setiathome.berkeley.edu. Another citizen astronomy project is Stardust at home where you help astronomers look for interplanetary dust grains on aerogels from the Stardust project. See http://stardustathome.ssl.berkeley.edu/ Here s what do do for this homework assignment. 1. Register as a Galaxy Zoo User. Go to http://galaxyzoo.org/ This is actually Galaxy Zoo Hubble the third phase of the project to collect galaxy classifications. Click on Register underneath Classifier Log In (see below). For your User Name and Display Name please give your firstname_lastname. So for example, if your name is Edwin Hubble your user and display name should be Edwin_Hubble. There are several people with the same last name in the class, so please use your first and last names.
Once you have registered and logged in, your results can be saved. 2. Read the instructions, and do the practice exercises. Click on The Story So Far, The Science and How to Take Part. The page called How to Take Part walks you through how to classify galaxies. Do their examples and figure out what they are looking for. 3. Classify Galaxies. Click on Classify Galaxies, and a galaxy will pop up for you to classify. Answer the questions indicated. Classify at least 50 galaxies. You do not have to do them at one sitting if you are logged on when you are classifying galaxies, it will keep your classifications for you to look at later on. For each galaxy you classify make notes in the attached table, as follows: a. In the color column, record the color of the galaxy as R for red or B for blue. Sometimes the galaxies look white, yellow or orange: for these, call them RED. After you do a few galaxies you should see some which are blue, and you ll see that blue galaxies are very blue looking. Blue galaxies are ones that have massive, young stars, whereas in the other galaxies, the stars are on average older, for reasons we talked about in class. b. In the type column, record S, for smooth and rounded, D for features a disk, A for Star or artifact. c. In the Spiral? column, if you classified the galaxy as having spiral arms, enter Y. d. In the Odd? column, put Yes if you said that there was something odd with the galaxy, No if you said there was nothing odd. e. In the Clumpy? column put Yes if you thought the galaxy was assymetrical and clumpy. If you do more than 84 galaxies, make copies of the table pages. Note that everybody gets assigned galaxies at random, so no two students will have exactly identical results for their classifications.
4. Print out My Galaxies. When you click on My Galaxies you get a page which shows you the galaxies you have classified. When I did this the other day after I did two galaxies, I got: You can click on the thumbnails of the galaxies and see more information about the galaxies you classified. When you have classified 50 galaxies or more, print out your My Galaxies page and attach it to your homework to turn in. On my printer it comes out with black text on white background.
TABLE: Galaxy Zoo Galaxy Classifications Color (R/B) Type (S/D/A) Spiral? (Y/N) Odd? (Y/N) Clumpy? (Y/N) Notes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
5. Analyze your results. Once you have finished classifying galaxies, write the total number of galaxies you ve classified here:. Now complete the following table: Red Galaxies Blue Galaxies Disk Galaxies Spiral Galaxies Spiral Galaxies that are Blue Spiral Galaxies that are Red Odd galaxies Clumpy galaxies Odd galaxies that are Red Odd galaxies that are Blue Clumpy galaxies that are Red Clumpy galaxies that are blue Number of galaxies You found Percentage of Total 6. What do you conclude from your findings above about the types of galaxies in the Universe?