Astronomy Picture of the Day

Explanation: Behold one of the most photogenic regions of the night sky, captured impressively. Featured, the band of our Milky Way Galaxy runs diagonally along the far left, while the colorful Rho Ophiuchus region including the bright orange star Antares is visible just right of center, and the nebula Sharpless 1 (Sh2-1) appears on the far right. Visible in front of the Milk Way band are several famous nebulas including the Eagle Nebula (M16), the Trifid Nebula (M20), and the Lagoon Nebula (M8). Other notable nebulas include the Pipe and Blue Horsehead. In general, red emanates from nebulas glowing in the light of exited hydrogen gas, while blue marks interstellar dust preferentially reflecting the light of bright young stars. Thick dust appears otherwise dark brown. Large balls of stars visible include the globular clusters M4, M9, M19, M28, and M80, each marked on the annotated companion image. This extremely wide field -- about 50 degrees across -- spans the constellations of Sagittarius is on the lower left, Serpens on the upper left, Ophiuchus across the middle, and Scorpius on the right. It took over 100 hours of sky imaging, combined with meticulous planning and digital processing, to create this image.