The Hubble Deep Field is one of the most extraordinary photographs ever taken. | IFLScience

Ultra Deep Field: Looking into Space, 12 Billion Years Back in Time | Hubble FriendsofNASA.org: This six-minute visual exploration of the Hubble Ultra Deep Field showcases the characteristics and contents of this landmark observation, as well as its four-dimensional nature across both space and time. In particular, galaxies are seen to more than 12 billion light-years away/12 billion years ago, allowing astronomers to trace the development of galaxies across cosmic time. A deep field is a long e