Abell 3827, a galaxy cluster located approximately 1.3 billion light-years away in the southern constellation of Indus, is so massive that its gravity bends light like a giant lens.
This Hubble image shows the giant galaxy cluster Abell 3827. Image credit: NASA / ESA / Hubble / R. Massey.
Galaxy clusters are fundamental building blocks of the Universe, like stars and galaxies.
Typically, they contain thousands of galaxies of all ages, shapes and sizes.
They have a mass of about one million billion times the mass of the Sun and form over billions of years as smaller groups of galaxies slowly come together.
At one point in time galaxy clusters were believed to be the largest structures in the Universe — until they were usurped in the 1980s by the discovery of superclusters, which typically contain dozens of galaxy clusters and groups and span hundreds of millions of light-years.
However, clusters do have one thing to cling on to; superclusters are not held together by gravity, so galaxy clusters still retain the title of the biggest structures in the Universe bound by gravity.
“Looking at this cluster of hundreds of galaxies, it is amazing to recall that until less than 100 years ago, many astronomers believed that the Milky Way was the only galaxy in the Universe,” Hubble astronomers said.
“The possibility of other galaxies had been debated previously, but the matter was not truly settled until Edwin Hubble confirmed that the Great Andromeda Nebula was in fact far too distant to be part of the Milky Way.”
“The Great Andromeda Nebula became the Andromeda Galaxy, and astronomers recognized that our Universe was much, much bigger than humanity had imagined.”
“We can only imagine how Edwin Hubble — after whom the NASA/ESA Hubble Space Telescope was named — would have felt if he’d seen this spectacular image of Abell 3827,” they said.
Abell 3827 was observed by the Hubble telescope in order to study dark matter, which is one of the greatest puzzles cosmologists face today.
The color image of the galaxy cluster was made from separate exposures taken in the visible and infrared regions of the spectrum with Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) instruments.
Four filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.