The team operating NASA's Hubble Space Telescope believes it may have uncovered renewed evidence of the fact that all galaxies are “embedded” in a cocoon of dark matter, the invisible substance that is believed to keep them and clusters all together. During a recent survey of the skies, the observatory has picked up the trace of a few dwarf galaxies in the Perseus cluster, which have remained intact and perfectly round, while larger ones around them were being ripped apart by the gravitational forces exerted by their neighbors.

What's most amazing is the fact that these smaller star aggregates have exhibited no signs of foreign influence, even if they have been located in the center of the cluster, the place where most forces act. This, scientists say, can only be explained by the presence of very large amounts of dark matter in the region, which have allowed these dwarf formations to retain their perfectly-round shape. Hubble has discovered a pretty significant number of such galaxies in the region, so astrophysicists' main guess is that they reside in a very concentrated “pool” of dark matter.

“We were surprised to find so many dwarf galaxies in the core of this cluster that were so smooth and round and had no evidence at all of any kind of disturbance. These dwarfs are very old galaxies that have been in the cluster a long time. So if something was going to disrupt them, it would have happened by now. They must be very, very dark matter-dominated galaxies,” University of Nottingham astronomer Christopher Conselice, who has been in charge of the latest observations, explains.

“With these results, we cannot say whether the dark-matter content of the dwarfs is higher than in the Milky Way Galaxy. Although, the fact that spiral galaxies are destroyed in clusters, while the dwarfs are not, suggests that is indeed the case,” he concludes in a study published in the March 1st issue of the journal Monthly Notices of the Royal Astronomical Society.

Hubble and the Chandra X-Ray Observatory continue to monitor galaxy clusters, as well as individual galaxies, in hopes of better determining how dark matter acts on them. For about 80 years, astronomers have believed that this elusive matter is the “scaffolding” on which the Universe was generated and now expands, and that the fact that it cannot be seen is not an evidence of it not being there.