Better known as M106 [ http://antwrp.gsfc.nasa.gov/apod/ap050730.html ], bright spiral galaxy NGC 4258 is about 30 thousand light years across and 21 million light years away toward the northern constellation Canes Venatici [ http://hawastsoc.org/deepsky/cvn/index.html ]. The yellow and red hues in this composite image [ http://chandra.harvard.edu/photo/2007/ngc4258/ ] show the galaxy's sweeping spiral arms [ http://en.wikipedia.org/wiki/Spiral_galaxies ] as seen in visible and infrared light. But x-ray [ http://chandra.harvard.edu/xray_astro/medxray.html ] and radio data [ http://www.nrao.edu/whatisra/index.shtml ] (blue and purple) reveal two extra spiral arms -- arms that don't align with the more familiar tracers of stars, gas, and dust [ http://antwrp.gsfc.nasa.gov/apod/ap070328.html ]. In fact, an analysis [ http://arxiv.org/abs/astro-ph/0106514 ] of the x-ray [ http://arxiv.org/abs/astro-ph/0701569 ] and radio data suggests that the anamolous arms are composed of material heated by shock waves. Detected at radio wavelengths, powerful [ http://antwrp.gsfc.nasa.gov/apod/ap030705.html ] jets originating in the galaxy's core likely drive the shocks into the disk of NGC 4258.