Read More: NASA is once again highlighting an image taken on July 3, 2025, from the ISS that looks like something out of a movie: a \u201cgigantic jet\u201d that doesn\u2019t fall to Earth, but instead shoots out of a storm and rises to a height of nearly 100 kilometers<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nIn the new work, a team led by statistician Dayi (David) Li at the University of Toronto<\/a> treated those clusters as clues instead of isolated objects. When they measured their positions and motions, they found that the four clusters move as if they orbit the same unseen center of gravity.<\/p>\n\n\n\nPreliminary measurements suggest that the galaxy shines with roughly the light of six million suns, yet the four clusters alone carry about 16% of that brightness. <\/p>\n\n\n\n
That unusually large share hints that something massive and invisible is holding everything together and places CDG\u20112 in the same family as other mysterious galaxies<\/a> that challenge standard ideas about how stars and dark matter should be mixed.<\/p>\n\n\n\nHow telescopes uncovered an almost invisible galaxy<\/h2>\n\n\n\n
To uncover this faint system, researchers combined images from NASA’s Hubble Space Telescope<\/a>, the Euclid space telescope<\/a> of the European Space Agency, and the Subaru Telescope in Hawaii.<\/p>\n\n\n\nOn their own, each observatory picked out only the bright star clusters, but together, after careful processing, they revealed a whisper of diffuse light connecting the clusters into a single dim galaxy.<\/p>\n\n\n\n![\"A](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/04\/dark-galaxy-cdg-2-discovery-perseus-cluster.jpg\" "\\"\\"")
By combining data from three major observatories, researchers confirmed that Candidate Dark Galaxy 2 (CDG-2) is held together by a massive, invisible halo of dark matter.<\/figcaption><\/figure>\n\n\n\nAn official release<\/a> describes how Euclid’s sensitivity to very faint structures and Hubble’s sharp vision work together to pick out barely there galaxies from the background noise. Subaru’s wide field of view helps map the crowded environment of the Perseus cluster, confirming that CDG\u20112 is not just a chance alignment of star clusters along our line of sight.<\/p>\n\n\n\nWhat makes CDG\u20112 so dark<\/h2>\n\n\n\n
From those data, astronomers estimate that between 99.94% and 99.98% of the galaxy’s mass must be dark matter<\/a> in order to keep the clusters bound. <\/p>\n\n\n\n\n\n\nRead More: James Webb discovers (once again) the most distant galaxy in the universe and breaks its own record<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nOnly a tiny fraction is made of ordinary matter, the kind that builds stars, planets, gas clouds, and everything we can see, so CDG\u20112 looks even more extreme than the Milky Way, whose halo is thought to be roughly 90% dark matter.<\/p>\n\n\n\n
Dark matter is the name given to a form of matter that has gravity but does not give off, block, or reflect light in any way we can easily detect. <\/p>\n\n\n\n
In galaxy clusters, its presence shows up in the way stars orbit and in how gravity bends light from more distant galaxies into stretched arcs or even nearly perfect rings<\/a>, a trick known as gravitational lensing.<\/p>\n\n\n\nWhy this ghost galaxy matters<\/h2>\n\n\n\n
For researchers, CDG\u20112 is more than a curiosity at the edge of visibility. It is a natural laboratory where they can test how dark matter clumps and how much invisible mass is needed to hold a system together. The same techniques that uncovered CDG\u20112 will likely reveal more nearly starless systems in the coming years.<\/p>\n\n\n\n
New space missions, from Euclid to the SPHEREx space telescope<\/a>, are mapping the sky in many colors of light and revealing faint structures that once slipped through the cracks. <\/p>\n\n\n\n\n\n\nRead More: Astronomers discover a baby galaxy in turbo mode: it converts more than 180 \u201csuns\u201d of gas per year into new stars… while ours barely reaches 1<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nAt the end of the day, CDG\u20112 shows that most of the universe does not look like the bright stars we see at night. A galaxy held together almost entirely by invisible matter is a reminder that the cosmos is still full of surprises.\u00a0<\/p>\n\n\n\n
The main study was published in The Astrophysical Journal Letters<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"Imagine a galaxy that barely shines, so faint it hides in the background glow of the universe. Astronomers now say … <\/p>\n
Preliminary measurements suggest that the galaxy shines with roughly the light of six million suns, yet the four clusters alone carry about 16% of that brightness. <\/p>\n\n\n\n
That unusually large share hints that something massive and invisible is holding everything together and places CDG\u20112 in the same family as other mysterious galaxies<\/a> that challenge standard ideas about how stars and dark matter should be mixed.<\/p>\n\n\n\n To uncover this faint system, researchers combined images from NASA’s Hubble Space Telescope<\/a>, the Euclid space telescope<\/a> of the European Space Agency, and the Subaru Telescope in Hawaii.<\/p>\n\n\n\n On their own, each observatory picked out only the bright star clusters, but together, after careful processing, they revealed a whisper of diffuse light connecting the clusters into a single dim galaxy.<\/p>\n\n\n\n An official release<\/a> describes how Euclid’s sensitivity to very faint structures and Hubble’s sharp vision work together to pick out barely there galaxies from the background noise. Subaru’s wide field of view helps map the crowded environment of the Perseus cluster, confirming that CDG\u20112 is not just a chance alignment of star clusters along our line of sight.<\/p>\n\n\n\n From those data, astronomers estimate that between 99.94% and 99.98% of the galaxy’s mass must be dark matter<\/a> in order to keep the clusters bound. <\/p>\n\n\n\n Only a tiny fraction is made of ordinary matter, the kind that builds stars, planets, gas clouds, and everything we can see, so CDG\u20112 looks even more extreme than the Milky Way, whose halo is thought to be roughly 90% dark matter.<\/p>\n\n\n\n Dark matter is the name given to a form of matter that has gravity but does not give off, block, or reflect light in any way we can easily detect. <\/p>\n\n\n\n In galaxy clusters, its presence shows up in the way stars orbit and in how gravity bends light from more distant galaxies into stretched arcs or even nearly perfect rings<\/a>, a trick known as gravitational lensing.<\/p>\n\n\n\n For researchers, CDG\u20112 is more than a curiosity at the edge of visibility. It is a natural laboratory where they can test how dark matter clumps and how much invisible mass is needed to hold a system together. The same techniques that uncovered CDG\u20112 will likely reveal more nearly starless systems in the coming years.<\/p>\n\n\n\n New space missions, from Euclid to the SPHEREx space telescope<\/a>, are mapping the sky in many colors of light and revealing faint structures that once slipped through the cracks. <\/p>\n\n\n\n At the end of the day, CDG\u20112 shows that most of the universe does not look like the bright stars we see at night. A galaxy held together almost entirely by invisible matter is a reminder that the cosmos is still full of surprises.\u00a0<\/p>\n\n\n\n The main study was published in The Astrophysical Journal Letters<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" Imagine a galaxy that barely shines, so faint it hides in the background glow of the universe. Astronomers now say … <\/p>\nHow telescopes uncovered an almost invisible galaxy<\/h2>\n\n\n\n
What makes CDG\u20112 so dark<\/h2>\n\n\n\n
Read More: James Webb discovers (once again) the most distant galaxy in the universe and breaks its own record<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
Why this ghost galaxy matters<\/h2>\n\n\n\n
Read More: Astronomers discover a baby galaxy in turbo mode: it converts more than 180 \u201csuns\u201d of gas per year into new stars… while ours barely reaches 1<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n