This schematic diagram shows how scientists think the universe has evolved from the Big Bang to the present day. Data from the UKIRT, VLT, and Subaru observatories allowed astronomers to take four precise and comparable snapshots of the universe when it was, 2, 4, 6 and 9 billion years old, each containing hundreds of star-forming galaxies. By comparing the different snapshots, astronomers were able to accurately track what has changed over the past 11 billion years. // illustration by CXC/NASA/NOAO/KIPAC