Tidal Tales

Gravity tends to sculpt galaxies into symmetrical shapes. But interactions with other galaxies can distort these shapes. As galaxies approach each other, their gravity pulls on each other’s stars, planets, gases, and dark matter in much the same way that our Moon’s gravity pulls on Earth’s oceans to create tides. The story told by the distorted shapes of galaxies gives astronomers clues to their history, including whether they have encountered or merged with one another.
Galaxy Zoo: Tidal Tales invites you to help read the story of galactic encounters in galaxy shapes. You will study beautiful images from the European Space Agency’s Euclid spacecraft, which is on a cosmological quest to explore the dark universe. Anyone with a cellphone or laptop can do this project.

Go to Project Website

project task

Examine images

division

Astrophysics/ Universe

where

Online

launched

2026

Against the backdrop of space and a smattering of small points of light, four pairs of galaxies are caught mid-merger. At least two distinct, bright nuclei are visible inside each pairing. The swirls of stars, planets, gasses surround each pair has taken on a wildly different appearance from one to another. The upper right pair resembles a single swish. The upper left shows two tear drops merging, their tails extending almost opposite each other. In the lower left, a heavy-lashed human eye-shaped blob has connected with a tadpole. In the lower right, just two tails spin off the two nuclei almost like two arms spinning off a single galaxy.

Three images of galaxy mergers like the ones you’ll classify as a Galaxy Zoo: Tidal Tales participant.

Euclid mission

What you'll do:

View images of galaxies taken by the Euclid Mission.
Learn how to identify the telltale evidence of galactic mergers in images of galaxies taken by the Euclid Mission
Answer a short series questions about each image to help scientists and enthusiasts worldwide build a clearer picture of how galaxies assemble and evolve over cosmic time.

Requirements

Time: Ten minutes to complete the tutorial
Equipment: internet connected computer, tablet, or smartphone
Knowledge: None. The website offers a tutorial and a Field Guide with a gallery of examples.

Get started!

Visit the project website.
Complete the in-project tutorial.
Start identifying the evidence of galactic interactions.

Learn more:

Visit Tidal Tales’ Education page for links to image galleries and websites to learn more about everything from galaxy basics to mergers, and the European Space Agency’s Euclid mission, which is the source of images used in this project.

Interested in more citizen science projects about galaxies? Try Galaxy Zoo or Redshift Wrangler.