By using these galaxy clusters as distance markers, astronomers can measure how quickly the Universe was expanding at different times since the Big Bang. According to Einstein's theory of general relativity, the rate of expansion is determined by the properties of dark energy plus the amount of matter in the Universe, where the latter is mostly made up of unseen material called dark matter.
This galaxy clusters was part of a large survey of over 300 clusters used to investigate dark energy, the mysterious energy that is currently driving the accelerating expansion of the universe.
Credits: X-ray: NASA/CXC/Univ. of Alabama/A. Morandi et al; Optical: SDSS, NASA/STScI
#nasa #space #galaxy #nasabeyond #astronomy #einstein #bigbang #darkmatter #universe #science