The image is a composite of separate exposures made by the WFC3 instrument on the Hubble Space Telescope. Three filters were used to sample broad wavelength ranges in the near infrared. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: F105W (Y) blue; F125W (J) green; F160W (H) red.
NASA/ESA/G. Illingworth/R. Bouwens/ HUDF09 Team