File:M101 combined low.jpg

English: First-light image from the Swift Gamma-Ray Burst Mission's UVOT instrument, of the M101 "Pinwheel" Galaxy. This UVOT image combines both ultraviolet and visible light from a number of filters. Each filter is sensitive to light of a different color, ranging from ultraviolet light beyond the range of human eyesight through the blue to yellow portion of the visible spectrum. This is a 'false-color' image with the shortest wavelength ultraviolet rays being represented as blue, and the longest visible light wavelengths as red. The image shows that hot young stars are being formed in abundance in M101, especially in the spiral arms of the galaxy, where they show up in ultraviolet light. The central regions of the galaxy have more cool, old stars, which appear 'red' in the picture. A number of foreground stars, located in our own Galaxy, also reveal themselves by their red color.