The image above shows us a star cluster officially designated NGC 2264, which is informally called the Christmas Tree Cluster. It's about 2,500 light years away, and features young stars between one and five million years old -give or take the 2,500 years it took the light to reach earth. The stars range from a tenth the size of our sun to seven times its size.
This is a composite picture, taken by three kinds of telescope cameras. The green is the gas among the nebula, taken by an optical camera from the National Science Foundation’s WIYN 0.9-meter telescope. Foreground and background stars in white were revealed by infrared data from the Two Micron All Sky Survey. The blue and white blinking lights are from X-rays detected by NASA’s Chandra X-ray Observatory. Did I say they blinked? They do, like twinkling tree lights, shown in an animation in the NASA article about the image. The twinkling effect was added for the video, but the stars really do twinkle, just not in sync with each other. That, and the choice to render the gas image in green, is NASA's Christmas gift to all of us. -via Bored Panda
(Image credits: X-ray: NASA/CXC/SAO; Optical: T.A. Rector (NRAO/AUI/NSF and NOIRLab/NSF/AURA) and B.A. Wolpa (NOIRLab/NSF/AURA); Infrared: NASA/NSF/IPAC/CalTech/Univ. of Massachusetts; Image Processing: NASA/CXC/SAO/L. Frattare & J.Major)