Astronomers have completed a massive survey of the Andromeda Galaxy using the Hubble Space Telescope, creating a unique 417-megapixel panorama. This work covered more than a decade and included more than 600 photographs. The result was a mosaic measuring 42208 × 9870 pixels – the largest image ever captured by Hubble.

The panorama captures more than 200 million stars — just a fraction of the trillion stars in the galaxy. Thanks to the details of the mosaic, which includes 2.5 billion pixels, scientists can further explore the history of Andromeda, particularly its mergers with other galaxies.
Andromeda’s historical role
The Andromeda Galaxy, the Milky Way’s closest neighbor, has long attracted the attention of astronomers. A century ago, Edwin Hubble proved that this object was outside the Milky Way and was a separate galaxy, which forever changed mankind’s view of the Universe. It was previously thought that the Milky Way was the entire Universe.
Andromeda is key to understanding the structure and evolution of our Galaxy. Huble images provide a unique opportunity to study the details of the galaxy as a whole, something that cannot be achieved with other large galaxies.

Principal investigator Ben Williams of the University of Washington notes that Hubble provides extremely detailed data that is vital to science. Even with the advent of the new James Webb telescope, Hubble remains an indispensable instrument for astronomy.
Herculean task
Photographing Andromeda has become an extremely difficult task because of its enormous size and relative proximity – 2.5 million light-years away. NASA calls this mission a “Herculean task.” It took more than a decade of work to create the mosaic.
The project began with the Panchromatic Hubble Andromeda Treasury (PHAT) program, which explored the northern part of the galaxy in the ultraviolet, visible, and infrared spectra. Subsequently, the Panchromatic Hubble Andromeda Southern Treasury (PHAST) program complemented the southern survey by adding data on about 100 million stars. Together, these programs covered the entire disk of Andromeda, which is visible from Earth at an inclination of 77 degrees.
Discoveries and future research
During the study, it was discovered that Andromeda experienced a merger with another galaxy that caused active star formation, but then the process stopped.
Despite its impressive achievements, the upcoming Nancy Grace Roman Space Telescope is expected to open new horizons in the study of the Universe. The observatory, equipped with wide-angle optics, will take the equivalent of 100 high-resolution Hubble photos per exposure. The Nancy Grace data, combined with information from the Hubble and James Webb telescopes, will help to further explore the Andromeda Galaxy and the Universe as a whole.
Earlier we reported that the Milky Way’s collision with the Andromeda galaxy was called into question.
According to NASA