The tangled arms of the Pinwheel galaxy, otherwise known as Messier 101, are decked out in red in this new infrared image from NASA's Spitzer Space Telescope.
The Pinwheel galaxy is located 27 million light-years away in the constellation Ursa Major. It is what's called a flocculent spiral, which means that its spiral arms are not well defined.
In this infrared composite, the red color shows the dust, while the blue glow around the galaxy is from starlight. Blue indicates light with a wavelength of 3.6 microns, green corresponds to 4.5 microns, and red to 5.8 and 8.0 microns. The contribution from starlight (measured at 3.6 microns) has been subtracted from the 5.8- and 8-micron images to enhance the visibility of the dust features.
Image Credit: NASA/JPL-Caltech
Explanation from: http://www.spitzer.caltech.edu/images/1945-ssc2008-14b-The-Pinwheel-Galaxy-M101-in-the-Infrared