Photograph
The Swan Nebula (M17)
A cosmic ocean of glowing gas and dust, located about 5,500 light-years from Earth in the constellation of Sagittarius. Also known as the Omega or Horseshoe Nebula, it is one of the most active stellar nurseries in our galaxy. Young, hot stars hidden deep within its core light up the hydrogen clouds, sculpting the distinctive silhouette of a swan gliding through deep space.
Beyond the frame
The bright shape resembling a swan is only the exposed surface of a much larger molecular cloud. Behind the glowing gas lie dense, cold regions hidden from visible light, where star formation continues. We are looking at the boundary between young stars already revealed and the cloud from which more will eventually emerge.