A historic moment for astronomy - more than 500,000 galaxies in one image

A historic moment has been achieved in astronomy with the release of a groundbreaking image capturing more than 500,000 galaxies in a single frame. The photograph, unveiled by the Vera C. Rubin Observatory, presents a deep view of the COSMOS field located in the constellation Sextans. This region of space has long been one of the most studied areas in the universe, and this new image offers a powerful new perspective on this well-known celestial landmark. The image was captured using the world's largest digital camera, the LSST Camera, which contains 3.2 gigapixels. It is mounted on the 8.4-meter Simonyi Survey Telescope. The image was created by combining hundreds of individual observations and includes over half a million galaxies and more than 50,000 stars. The field covers approximately 3,000 square degrees of the southern sky, roughly one-sixth of the southern hemisphere’s sky. For comparison, the full Moon covers about one-fifth of a single square degree. The COSMOS image encompasses an area equivalent to 15,000 full Moons placed side by side. The COSMOS field holds particular value for astronomers because it lies beyond the plane of our Milky Way galaxy. As such, telescopes can observe a vast number of distant galaxies, some of which are billions of light-years away. Looking deeper into space also means looking further back in time, allowing scientists to study galaxies in various stages of cosmic history. Astronomers have been studying the COSMOS field for over two decades. Beginning with observations from the Hubble Space Telescope in 2003, researchers around the globe have directed numerous leading global telescopes onto the same area, examining it across a wide range of wavelengths, from radio waves to gamma rays. Because the field has been so extensively observed, it serves as a crucial reference point for testing new data, comparing measurements, and integrating information from many observatories. Multiple imaging sessions of the COSMOS field using the LSST Camera will build upon earlier observations, adding a dynamic perspective to the field. This approach will help astronomers examine not only how distant galaxies appear but also how the night sky changes over time. “The deep image of COSMOS is just the beginning,” said Bob Blum, director of the Vera C. Rubin Observatory at NSF NOIRLab. “Repeated visits to the site over the coming years will demonstrate the power of our research design in uncovering transient and variable objects such as supernovae and other explosive transients, enabling detailed tracking and study.” This new view of COSMOS provides early insight into future scientific endeavors, offering an exceptionally deep and broad look into the cosmos. It reveals an enormous population of distant galaxies and captures the ever-changing sky above Earth.