Hubble shears a "woolly" galaxy

This new image of the spiral galaxy NGC 3521 from the NASA/ESA Hubble Space Telescope is not out of focus. Instead, the galaxy itself has a soft, woolly appearance as it a member of a class of galaxies known as flocculent spirals .

Like other flocculent galaxies, NGC 3521 lacks the clearly defined, arcing structure to its spiral arms that shows up in galaxies such as Messier 101 , which are called grand design spirals . In flocculent spirals, fluffy patches of stars and dust show up here and there throughout their discs. Sometimes the tufts of stars are arranged in a generally spiralling form, as with NGC 3521, but illuminated star-filled regions can also appear as short or discontinuous spiral arms.

About 30 percent of galaxies share NGC 3521's patchiness, while approximately 10 percent have their star-forming regions wound into grand design spirals.

NGC 3521 is located almost 40 million light-years away in the constellation of Leo (The Lion). The British astronomer William Herschel discovered the object in 1784. Through backyard telescopes, NGC 3521 can have a glowing, rounded appearance, giving rise to its nickname, the Bubble Galaxy.