A new mapping of our galaxy has just revealed cosmic landscapes never seen before—a Milky Way with supernatural colors that transcends its simple appearance as a milky streak in the night sky. This unprecedented vision, born from the collaboration between two observation campaigns and unprecedented computer processing, allows astronomers to gain a new perspective on the fundamental mechanisms that govern stellar life.
This exceptional representation is the culmination of many years of observations conducted with the Murchison Widefield Array radio telescope, located in the preserved expanses of Western Australia. The study, published in
Publications of the Astronomical Society of Australia, marks a significant step in our understanding of galactic structure by combining for the first time the complementary advantages of the GLEAM and GLEAM-X surveys. This data fusion required extremely complex calculations to harmonize observations collected at different periods.
The genesis of a composite image
The Murchison Widefield Array radio telescope, with its 4,096 antennas spread over several square kilometers (several square miles), scanned the southern sky between 2013 and 2020. The first campaign, named GLEAM, aimed to establish a general mapping of the entire visible sky in the southern hemisphere. This approach provided an overall view but lacked the precision to distinguish the finer structures that make up the galactic plane—the central region where most stellar activity is concentrated.
The second campaign, GLEAM-X, benefited from substantial technical improvements that allowed for much higher resolution. However, this increased precision came at the expense of overall coverage, creating a natural complementarity between the two datasets. Astronomers therefore developed an innovative method, called
image domain gridding, specifically designed to merge these two partial views into a coherent and detailed image.
The data integration process represented an unprecedented challenge, mobilizing over a million hours of computation on the Pawsey Supercomputing Research Centre's supercomputers. The algorithm had to correct distortions induced by Earth's ionosphere, which affect radio waves differently depending on atmospheric conditions and observation periods. This rigorous processing resulted in a mosaic covering 95% of the southern galactic plane.
The meaning of cosmic colors
The final image stands out for its extended chromatic spectrum, where each hue corresponds to a specific radio frequency and reveals distinct astrophysical phenomena. The dominant orange tones betray the presence of supernova remnants—expanding gaseous shells resulting from the violent explosion of stars at the end of their lives. These structures, particularly bright at low frequencies, appear as vast circles glowing intensely in the galactic landscape.
The bluish regions, more localized, signal stellar nurseries where new stars are born. This specific coloration comes from the radio emission of dense molecular clouds where the temperature exceeds several thousand degrees. Between these two extremes, the greenish areas correspond to intermediate frequencies and highlight hybrid structures where different astrophysical processes coexist.
This colorimetric coding allows for immediate identification of the major components of our galaxy, providing researchers with a visual tool that is immediately interpretable. The ability to clearly distinguish star-forming regions from the remnants of deceased stars opens new perspectives for studying the life cycle of stars. This representation goes far beyond the aesthetic framework to become a full-fledged scientific analysis instrument.
Article author: Cédric DEPOND