Galaxy Zoo

Citizen Scientists Classify Galaxies



Galaxy Zoo is an online astronomy Citizen Science project which invites members to classify millions of galaxies personally by hand.

The Citizen Scientists are tasked with ordering galaxies into different categories: elliptical and spiral. In the case of spiral galaxies, a distinction can be made between clockwise rotation and anti-clockwise rotation. No astronomical expertise is needed. Tutorials are held to explain the different galaxy types to the volunteers. They then practice on example pictures and afterwards check their results. Sometimes pictures of meteorite tails appear as contrasting straight lines in the picture or pictures of a single, large colored star can be seen.

The images of the galaxies are automatically recorded by the Sloan Digital Sky Survey using a digital camera mounted on a telescope which is located at the Apache Point Observatory in New Mexico, USA.

It is hoped that this public participation will provide valuable information on the distribution of different types of galaxies, giving scientists the chance to review and expand current galaxy models.

In the past, scientists could not rely on computer programs to correctly classify galaxies automatically. As the human brain is much more powerful than a computer program in pattern recognition, the contributions provided by over 350,000 human volunteers known as the “Zooites” has enabled researchers to work through vast sets of data. Now, with the current progress in artificial intelligence, the role of the Citizen Scientists in astrophysics will probably change in future to training and working with AI.


Project member:

Prof. Dr. Kevin Schawinski, Institute for Astronomy, ETH Zurich


Graphic artist:

Lazar Jeremic