October 2, 2003: The Hubble Heritage team of astronomers, who assemble many of the NASA Hubble Space Telescope's most stunning pictures, is celebrating its five-year anniversary with the release of the picturesque Sombrero galaxy. One of the largest Hubble mosaics ever assembled, this magnificent galaxy has an apparent diameter that is nearly one-fifth the diameter of the full moon. The team used Hubble's Advanced Camera for Surveys to take six pictures of the galaxy and then stitched them together to create the final composite image. The photo reveals a swarm of stars in a pancake-shaped disk as well as a glowing central halo of stars.See the rest:
The Sombrero, named because it resembles a broad-brimmed Mexican hat, is oriented nearly edge-on to us. This edge-on view reveals that the disks of spiral galaxies are incredibly thin. The disk displays dark dust lanes, where many young and bright stars reside. The Hubble telescope also shows that the glowing central bulge of stars harbors nearly 2,000 globular clusters of stars, 10 times as many as orbit our Milky Way galaxy.
The Hubble Heritage Project team, made up of astronomers and image processing specialists from the Space Telescope Science Institute, has been releasing an image from the Hubble Space Telescope every month since 1998. Monthly image candidate come from previously unreleased data from the Hubble telescope's photo archive as well as new observations, like those of the Sombrero galaxy, that are taken by the Heritage team for outreach purposes.
The angular diameter (or the apparent size) of an object is an expression of how wide an object appears to be. The moon is a fixed distance from us and has a fixed inherent size (diameter). The Sombrero galaxy is also of a fixed size and distance. Thus, we can compare their apparent sizes. By saying that the Sombrero galaxy is one-fifth of the diameter of the full moon, that means that if you were able to see the Sombrero galaxy with the naked eye, you could take 5 of them and line them up end to end, and what you see in the sky from these 5 galaxies all lined up equals the same length as the diameter of the full moon.