About the project

What is this project?

This is a citizen-science project where volunteers visually classify galaxies in telescope images. Your classifications help astronomers measure galaxy morphologies at scales that would be impossible for a small research team to do alone.

Why do you need humans? Can’t an algorithm do this?

Machine-learning models are powerful, but they still need high-quality training labels and independent validation. Humans are excellent at recognizing complex, messy, or rare structures (e.g., mergers, bars, tidal features) that are hard to capture with simple rules.

What science questions are you trying to answer?

Goals include: how galaxy shapes relate to star formation, environment, and cosmic time; how bars and bulges form; how mergers transform galaxies; and how morphology connects to structure and evolution.

Where do the images come from?

Images are cutouts from DECam, processed into a consistent format for classification. We may show different filters/bands or composites depending on availability.

Getting started

How do I begin?

Click 'Get Started' and answer the questions shown for each galaxy. Each task is quick. Most take ~10–30 seconds.

Do I need astronomy experience?

No. The workflow is designed so that anyone can contribute. You’ll improve quickly with practice.

How many galaxies should I classify?

You can classify as many galaxies as you like! There's no target or limit for an individual classifier, so you are free to pick your own target. You could classify many galaxies at once, or try to contribute one or two each day. Each and every jellyfish galaxy helps us expand our understanding, so we appreciate every classification you make!

Is there a tutorial or field guide?

Yes. Please use the built-in Tutorial and the Field Guide (available on each task) for examples of bars, spiral arms, mergers, edge-on disks, and common artifacts.

When classifying galaxies

What features am I looking for?

You'll see the most common features of galaxies in the tutorial, as well as in the "Need some help with this task?" panels for each task. Whilst all galaxies are different, these should help you understand what features to look for.

What if I can't see a galaxy?

If the galaxy is not clear, obscured by a star, or the image is not clear to the extent that you can't classify the galaxy, you'll have the option to select in the first task.

There are other objects in the image, is this a merger?

There will almost always be other objects in the field of view, usually small galaxies, or foreground stars. Galaxies likely to be interacting with the main object will usually be fairly similar in size, and sometimes disturbed as well. Very small objects in the image are unlikely to be related to the main galaxy.

The galaxy looks edge on and I can't see any features! Can I still classify it?

If the galaxy is edge-on, you'll probably not be able to see spiral arms, however, in some cases, other features will still be visible! If the galaxy appears to be edge-on, do the best you can with any features you can still see.

I'm still having trouble classifying a galaxy, what can I do?

You can always ask a question in "Talk", to discuss it with other classifiers or members of our team, we're always happy to take a look and help with the challenging cases.