How a Galaxy’s Neighborhood Changes Its Shape

By Space.Fan Editorial DeskSeptember 17, 2026 at 4:00 AM UTC

Astronomers discovered that a galaxy’s size and surroundings play a major role in determining its final shape.

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The Drop

Galaxies come in many shapes, but they generally fall into two groups: flat, spinning disks or rounded, blob-like collections of s. Scientists have long wondered if a galaxy's location in the vast, web-like structure of space affects its shape. To find out, researchers studied 13,000 galaxies using images from the Hubble Space Telescope. They looked at how far each galaxy lived from the dense 'nodes' and thin 'filaments' that make up the cosmic web. They found that for large, massive galaxies, location matters a lot. If a big galaxy is near a busy node, it is more likely to be a rounded, blob-like shape. This is likely because being near a node makes it harder for the galaxy to spin smoothly and increases the chances of crashing into other galaxies. However, this pattern changes for smaller, dwarf-sized galaxies. Whether a dwarf galaxy is near a node or far out in empty space, it does not seem to change its shape as much. This suggests that the environment is very important for giants, but small galaxies mostly grow based on their own internal processes.

Why It Matters

This study helps us understand the 'nature versus nurture' debate for galaxies. It confirms that for massive galaxies, the neighborhood they live in forces them to change their structure over time. By showing that this effect disappears for smaller galaxies, researchers have identified a key dividing line in how different types of galaxies evolve throughout the life of the universe.

The Catch

While this study looked at a large number of galaxies, it only observed them in a specific slice of time. Because galaxies change very slowly, the researchers are observing snapshots rather than watching a single galaxy grow. Future studies will need to model how these galaxies change over billions of years to be certain about the causes.

Put That in Perspective

Scientists have been mapping the cosmic web for years, but this is one of the first times they have used such a large and detailed sample to compare both giant and dwarf galaxies. Researchers plan to use this data to better understand how galaxy collisions and neighborhood crowding stop stars from forming.

Source September 17, 2026

Ilin Lazar, Sugata Kaviraj, Aaron E. Watkins, Christopher J. Conselice, Darshan Kakkad, Thomas M. Sedgwick, Garreth Martin, Sophie Koudmani

Monthly Notices of the Royal Astronomical Society·10.48550/arXiv.2609.17662

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