Some of the galaxies in this image (two small ellipses at the 9 o’clock position) are ~1 billion light-years distant. The large galaxy in the center is the barred spiral galaxy NGC4725 which is “only” 40 million light-years distant. The smaller spiral galaxy at the 5 o’clock position is NGC4712 and is ~200 million light-years distant. Galaxy distances are measured in a number of ways including angular size, redshift and known star brightness for special stars known as cepheids and supernovae. By measuring the peak brightness of a supernova you can determine galaxy distances up to 10 billion light-years!