This illustration shows the wealth of information on scales both small and large available in the SDSS-III's new image. The picture in the top left shows the SDSS-III view of a small part of the sky, centered on the galaxy M33. The middle top picture is a further zoom-in on M33, showing the spiral arms of this galaxy, including the blue knots of intense star formation known as "HII regions." The top right-hand picture is a further zoom into M33 showing the object NGC 604, which is one of the largest HII regions in that galaxy. The figure at the bottom is a map of the whole sky derived from the SDSS-III image, divided into the northern and southern hemispheres of our galaxy. Visible in the map are the clusters and walls of galaxies that are the largest structures in the entire universe.
M. Blanton and the SDSS-III