W3 is a region where many massive stars are forming in a string of stellar clusters, located about 6,000 light years from Earth in the Perseus arm of the Milky Way galaxy. In this composite image, green and blue represent lower and higher-energy X-rays, respectively, while red shows optical emission. Hundreds of X-ray sources are revealed in this central region of W3 Main. These bright point-like objects are an extensive population of several hundred young stars, many of which were not found in earlier infrared studies.