By scrutinising the Hubble Ultra Deep field - the deepest image of the sky ever made - the NASA/ESA Hubble Space Telescope and the NASA Spitzer Space Telescope have joined forces to discover nine of the smallest, faintest, most compact galaxies ever observed in the distant Universe. Credit: ESA/Hubble (M. Kornmesser & L. L. Christensen), Hubble Ultra Deep Field and GOODS Flythroughs: NASA, ESA and F. Summers (STScI).
