From NASA astronomers comes the art of the long exposure: In this case, an ultraviolet image of the relatively nearby (2.9 million light years distant) Triangulum Galaxy, also known as M33.
The image here is a mosaic, taken from 39 separate frames with more than 11 hours of exposure time using the Swift satellite's Ultraviolet/Optical Telescope telescope.
NASA astronomer Steven Immler, who is responsible for the photo, calls it "the most detailed ultraviolet image of an entire galaxy ever taken." And indeed, the high resolution shows clear gas clouds and star-forming regions, even in the crowded heart of the galaxy.
The Triangulum is an excellent candidate for such ultraviolet-based photography. It is full of young star-forming regions – much more so than our own Milky Way – which emit relatively large amounts of ultraviolet light.
As is clear from the picture, it's a spiral like our own home galaxy, and is part of what's called the "Local Group" of galaxies that also includes the Andromeda Galaxy. It's much smaller than the Milky Way, however, with only about one-tenth the mass.
NASA's Swift Satellite Catches a Galaxy Ablaze With Starbirth [NASA press release]
(Image: The Triangulum Galaxy, as seen in ultraviolet light. Credit: NASA/Swift Science Team/Stefan Immler)
