Galaxy Zoo: Classifying Galaxies

By Jenny Moore (a 2016 Adler Astro-Journalist)

Galaxy Zoo is a civil science project that teaches people about the different types of galaxies in the universe. There are ones with smooth edges, or swirl patterns, or ones that have undefined shapes. There can also be unusual qualities in the image of a galaxy, such as an odd pattern, or large center bulge. This project also teaches civilians that each galaxy is slightly different, just like a fingerprint! Throughout the project, one can discover how galaxies are formed, and what the astronomers connected with the project are trying to understand. Galaxy Zoo’s goal is to study different galaxies and understand how the formation of galaxies affects the universe around us. Over time, the interactive galaxy classifying ‘game’ has matured from just identifying the galaxy’s shape, to identifying its key features, and even using images from special cameras that measure dark energy!

JennyP1F2 Figure 1: Above you can see different examples of galaxies and the different shapes they come in.


This project has evolved and each stage gradually gets more complex for the civil scientists. Galaxy Zoo started with images collected from the Sloan Digital Sky Survey, which created the most detailed 3D map of the universe. When the project began, it asked civilians to complete much simpler tasks. All one had to do was classify the shape of the Galaxy. The second stage of the project called for a more precise description of each image. It asked civilians to describe the arms of spiral galaxies, the size of their center bulges, etc. The third stage drew imaged from the Hubble telescope as well as the SDSS. Recently, scientists have combined the images from the Hubble surveys and the SDSS to create the most detailed imaged possible.


This project now uses images from the Dark Energy Camera Legacy (DECal) Survey, in addition to using the Hubble and SDS surveys. These cameras are the most sensitive and widest cameras used in the process of collecting images for this project. Since these camera’s are so sensitive, they produce images that are much clearer and more defined than the SDSS or Hubble surveys ever did, as shown in the image below. Galaxy Zoo has begun using these images to get the most accurate results in their study. Dark Energy Camera’s are used to not only make the clearest images of the universe, but they also measure dark energy.  Dark matter, and dark energy, make up a large portion of our universe. The DECaL survey uses infrared technology to create a map of our universe. The Dark Energy Camera Legacy Survey’s main focus is to collect the brightest images of faraway galaxies that cannot be seen with the naked eye. This survey is creating a layout of the universe by combining images of the night sky at different points in Earth’s rotation. The DECaLS project got me thinking about dark energy, because another aspect of this ‘map’ DECaLS is creating, is measuring the amount of dark matter and energy the universe is made of. I, personally, find this quite amazing because dark energy is a mystery to astrophysicists. It makes up over half of the universe, and yet no one knows what it is or where it comes from!

JennyP1F1 Figure 2: On the left is an image from the SDSS survey, and on the right is an image from the DECal survey. Both images are of the same galaxy.

Through the Galaxy Zoo project, civilians are helping scientist further understand the universe around us. By using clarified images from the DECaL survey, the scientist behind Galaxy Zoo can get the most accurate classifications from civilian’s submissions.  The classifying galaxy ‘game’ is helping categorize images of certain types of galaxies, and also figure out where large amounts of dark energy are. The clearer the images are, the more precise the classifications are. So get out there and start classifying!

Image sources:

Figure 1:


New images for Galaxy Zoo! Part 1 – DECaLS


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