When you buy through links on our articles, Future and its syndication partners may earn a commission.NASA’s Spitzer Space Telescope’s infrared cameras imaged the Milky Way’s center to create this portrait of our galaxy. | Credit: NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center/Caltech)An enormous supercluster made up from over 20 individual galaxy clusters hiding behind our dusty Milky Way is even larger than astronomers had thought, affecting the motion through space of all the galaxies and galaxy clusters in our corner of the cosmos.The Vela Supercluster was discovered in 2016 thanks to a team led by Renée C. Kraan-Korteweg of the University of Cape Town in South Africa. Some 870 million light-years away, it lurks close to the plane of the Milky Way. Extragalactic astronomers refer to a region behind our Milky Way as the ‘Zone of Avoidance’ because dust between our galaxy’s stars blots out, or deeply reddens, light from more distant galaxies behind it.AdvertisementAdvertisementGiven that this Zone of Avoidance takes up about 20% of the entire sky from our vantage point on Earth, that’s a lot of celestial real estate inaccessible to us.Fortunately, astronomers have their ways and means of bypassing the Zone of Avoidance, and now, Kraan-Korteweg and her team have done just that to discover the true scale of the vast Vela Supercluster.Gravity from huge superclusters tugs on the motions of galaxies across the universe, drawing them closer. We see these subtle galaxy motions as ‘cosmic flows’, like tides and eddies that carry galaxies this way and that.However, while we knew the Vela Supercluster was exceptionally massive when it was discovered, it didn’t seem massive enough to account for all the cosmic flows seen by astronomers.AdvertisementAdvertisementThe CosmicFlows catalogue, organized by astronomers in France and Hawaii, is a record of measurements of the ‘peculiar’ motions of galaxies, or rather, their motions that deviate from that expected by the continuous expansion of space. Once gravitational interactions with nearby galaxies have been accounted for, any excess peculiar motion is therefore the result of ‘cosmic flows’ — the gravitational attraction across hundreds of millions or even billions of light-years towards large centers of mass.There are many cosmic flows across the universe as streams of galaxies head in one direction or another. The ‘Great Attractor,”–– the romantic name given to one large supercluster also hidden by the Zone of Avoidance and connected to the Laniakea supercluster of which the Milky Way is a tiny part — is just one source of cosmic flow. The Shapley Supercluster, located 650 million light-years away, is another.A map of the galaxy superclusters in our neck of the cosmic woods. The two main dense cores of the Vela Supercluster can be seen. | Credit: Dr Jérôme Léca, RSA Cosmos, St Etienne, France.Now, Kraan-Korteweg and her astronomers, in a study led by Amber Hollinger of the Lyon 1 Claude Bernard University in France, have discovered the origin of the excess cosmic flow: the Vela Supercluster is larger than was thought.By using 65,518 galaxy distance measurements from the latest CosmicFlows catalog …
