2. The image below shows the spiral galaxy M74, located about 55 million light-years from the Earth in the constellation Pisces (the Fish). It is actually a superposition of two false- colour images: the red portion is from an optical image taken at visible wavelengths, while the blue portion is from an ultraviolet image made by NASA's Ultraviolet Imaging Telescope, which was carried into orbit by the space shuttle Colombia during the Astro-1 mission in 1990. Compare the visible and ultraviolet portions in the image, and from what you know about stellar evolution and spiral structure, explain the differences you see. (10 marks) Image Credit: Astronomical Society of the Pacific