'2.5 billion pixels': NASA's Hubble Space Telescope captures the best image of Andromeda Galaxy to date

Produced by Tarun Mishra

Decade-Long Effort

Astronomers completed a 10-year project to assemble a complete portrait of the Andromeda galaxy. The result is a detailed panoramic image, the most comprehensive view of the galaxy ever captured.

Largest Photomosaic

The mosaic required more than 600 overlapping snapshots over 1,000 Hubble Space Telescope orbits. The final image spans 2.5 billion pixels and showcases the glow of 200 million stars, only a fraction of Andromeda's stellar population.

Full View of Andromeda


The project began in 2015 with a focus on the galaxy's northern half, followed by the southern half. Zhuo Chen of the University of Washington explained that the new southern observations added nearly 100 million stars to the mosaic.

Significance

At 2.5 million light-years from Earth, Andromeda is the closest spiral galaxy to the Milky Way. Its size in the night sky is six times the diameter of the full moon, requiring extensive imaging to capture its entirety.

Galaxy Evolution


This image provides valuable data to study Andromeda's turbulent history, including its mergers with smaller satellite galaxies. Researchers aim to use Hubble's observations of star age, mass, and chemical composition to refine models of galaxy formation and evolution.

Galactic Collisions


Astronomers believe Andromeda’s southern half shows signs of a major merger 2–4 billion years ago, leading to unique star formation patterns. By contrast, the northern half is relatively undisturbed, supporting the theory of a significant collision in its past.

Published Findings

The research, published in The Astrophysical Journal, highlights Andromeda's complex structure and its potential to provide insights into galactic dynamics. The image also offers a foundation for future studies on how galaxies evolve after major interactions.