This image displays several merging galaxies (identified by the green circles) found in different regions of a large survey known as the All-Wavelength Extended Groth Strip International Survey (AEGIS). Hubble's Advanced Camera for Surveys took the image in 2004 and 2005. The galaxies reside at a range of distances from Earth, from 2.4 billion to 6.2 billion light-years away.
By studying many galaxy interactions at various distances from Earth, astronomers can measure the rate at which galaxies merge over time. This information yields important clues about how galaxies have changed throughout the universe's history.