What you’re looking at above is the sharpest and largest Hubble image ever taken. It stretches 48,000 light-years across the Andromeda Galaxy’s disk, and shows more than 100 million stars. This galaxy may be located 2.5 million light-years from Earth, but since Andromeda fills up so much of Hubble’s field of view, it was able to capture incredible detail in its survey of the galaxy. “Hubble traces densely packed stars extending from the innermost hub of the galaxy. Moving out from this central galactic bulge, the panorama sweeps from the galaxy’s central bulge across lanes of stars and dust to the sparser outer disk,” said a Hubble representative.
According to Space.com, “The panorama was created as part of the Panchromatic Hubble Andromeda Treasury (PHAT) program. This image was created as a mosaic of 7,398 exposures taken over the course of 411 pointings of the telescope, according to Hubble officials.”