---
title: "Galaxy Zoo"
chunk: 3/5
source: "https://en.wikipedia.org/wiki/Galaxy_Zoo"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:49:12.688307+00:00"
instance: "kb-cron"
---

=== Galaxy Zoo 2 ===
This consisted of some 250,000 of the brightest galaxies from the Sloan Digital Sky Survey. Galaxy Zoo 2 allowed for a much more detailed classification, by shape and by the intensity or dimness of the galactic core, and with a special section for oddities like mergers or ring galaxies. The sample also contained fewer optical oddities. The project which collected classifications from February 2009 - April 2010 and closed with some 60 million classifications.

=== Galaxy Zoo mergers ===
This studied the role of interacting galaxies. Interacting galaxies are galaxies that exhibit a gravitational influence on one another. This influence is exhibited over the course of millions or even billions of years as two or more galaxies pass nearby one another. The near passage of two massive structures can cause the galaxies to be distorted and possibly merge. The Galaxy Zoo Mergers aimed to provide a set of tools that allowed users to randomly sample various sets of simulation parameters in rapid succession by showing 8 simulation outputs at a time. This started in November 2009 and was retired in June 2012.

=== Galaxy Zoo supernovae ===
Galaxy Zoo used images partner from the Palomar Transient Factory to find Supernovae. The task in this Galaxy Zoo project was to help catch exploding stars – supernovae. Data for the site was provided by an automatic survey in California at the Palomar Observatory. Astronomers followed up on the best candidates at telescopes around the world. This started in August 2009 and was retired in August 2012.

=== Galaxy Zoo Hubble ===
The site's third incarnation, Galaxy Zoo Hubble, drew from surveys conducted by the Hubble Space Telescope to view earlier epochs of galaxy formation. In these surveys, which involve many days of dedicated observing time, we can see light from galaxies which has taken billions of years to reach us. The idea behind Galaxy Zoo Hubble was to be able to compare galaxies then to galaxies now, giving us a clear understanding of what factors influence their growth, whether through mergers, active black holes or simply star formation. This started in April 2010 and was retired in September 2012.
In October 2016, a study titled: "Galaxy Zoo: Morphological Classifications for 120,000 Galaxies in HST Legacy Imaging" was accepted for publication by the journal Monthly Notices of the Royal Astronomical Society. The abstract begins: "We present the data release paper for the Galaxy Zoo: Hubble project. This is the third phase in a large effort to measure reliable, detailed morphologies of galaxies by using crowdsourced visual classifications of colour composite images. Images in Galaxy Zoo Hubble were selected from various publicly-released Hubble Space Telescope Legacy programs conducted with the Advanced Camera for Surveys, with filters that probe the rest- frame optical emission from galaxies out to z ≈1."

=== Galaxy Zoo 4 ===
Galaxy Zoo 4 combined new imaging from the Sloan Digital Sky Survey with the most distant images yet from the Hubble Space Telescope CANDELS survey. The CANDELS survey makes use of the new Wide Field Camera 3 to take ultra-deep images of the universe. The project also includes images taken with the United Kingdom Infrared Telescope in Hawaii, for the recently completed UKIDSS project. UKIDSS is the largest, deepest survey of the sky at infrared wavelengths. Kevin Schawinski explained that: "The two sources of data work together perfectly: the new images from Sloan give us our most detailed view of the local universe, while the CANDELS survey from the Hubble telescope allows us to look deeper into the universe's past than ever before."
In October 2016, a paper was accepted for publishing in MNRAS titled: "Galaxy Zoo: Quantitative Visual Morphological Classifications for 48,000 galaxies from CANDELS". Quoting: "We present quantified visual morphologies of approximately 48,000 galaxies observed in three Hubble Space Telescope legacy fields by the Cosmic And Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and classified by participants in the Galaxy Zoo project. 90% of galaxies have z < 3 and are observed in rest-frame optical wavelengths by CANDELS. Each galaxy received an average of 40 independent classifications, which we combine into detailed morphological information on galaxy features such as clumpiness, bar instabilities, spiral structure, and merger and tidal signatures."

=== Radio Galaxy Zoo ===

On 17 December 2013, Galaxy Zoo opened a project called Radio Galaxy Zoo. It uses observations from the Australia Telescope Large Area Survey in Radio, and compares them to the Spitzer Space Telescope's infrared data. There are about 6000 images to look through. The CSIRO press release states that Radio Galaxy Zoo is a new citizen science project that lets anyone become a cosmic explorer. It continues that by matching galaxy images with radio images from CSIRO's Australia Telescope, a participant can work out if a galaxy has a supermassive black hole.

=== Other projects ===
Another project that uses data from volunteer classifications is Galaxy Zoo Quench, which studies the interactions between galaxies and the effect it has on starbursts (among others).

== Active projects ==

=== Galaxy Zoo James Webb Space Telescope ===
The current incarnation of Galaxy Zoo uses volunteers to classify hundreds of thousands of images taken by James Webb Space Telescope's COSMOS-Web survey, which is a large extragalactic survey imaging galaxies in the COSMOS field at extremely early cosmic times. An earlier iteration of Galaxy Zoo using data from JWST's Cosmic Evolution Early Research (CEERS) survey was used as a pilot for this project, and helped to establish the existence of stable disc galaxies at redshift 7.4, or just 700 million years after the Big Bang.

=== Complete list of projects ===
As of March 2026, the full list of Galaxy Zoo projects is: Galaxy Zoo 1, Galaxy Zoo 2, Galaxy Zoo Mergers, Galaxy Zoo Supernovae, Galaxy Zoo Hubble, Galaxy Zoo CANDELS, Radio Galaxy Zoo, Galaxy Zoo Quench, Galaxy Zoo DECALS 1, Galaxy Zoo DECALS2 + SDSS, Illustris, UKIDSS, Galaxy Zoo Bar Lengths, FERENGI, GAMA, Cosmic Dawn, Euclid, CEERS, and JWST.