This image of the spiral galaxy Messier 101 is a composite of views from NASA’s Great Observatories: Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory.
• The red color shows Spitzer’s view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form.
• The yellow color is Hubble’s view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes.
• The blue color shows Chandra’s view in X-ray light. Sources of X-rays include million-degree gas, exploded stars, and material colliding around black holes. (source)