An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports the discovery of the most densely populated galaxy cluster in formation in the early universe. A team of researchers used the OSIRIS instrument of the Gran Telescopio Canarias (GTC) to observe an area around the galaxy HDF850.1, already well known because it’s been the focus of various researches, discovering other protogalaxies. We see those galaxies as they were about 12.5 billion years ago, when the universe was very young, so this is a great discovery to study the birth and evolution of the largest structures in the universe.