Caption

Young galaxies. Part of the Hubble Deep Field showing distant, faint young galaxies as seen by the Hubble Space Telescope (HST). These galaxies are embedded in the frame as tiny, dim blobs. However, scientists have identified several collections of stars which are larger than clusters but smaller than galaxies. The size, combined with their age (16% of the current age of the Universe) suggests that these blobs may be galactic building blocks which later formed true galaxies. This Deep Field image took more than one day to expose, during which time the HST made 48 orbits of the Earth.