NGC 6559, Nebula East of Lagoon

NGC 6559, Nebula East of the Lagoon  NGC 6559 is a cloud of gas and dust located at a distance of about 5000 light-years from Earth, in the constellation of Sagittarius (The Archer). It is just east of the famous Lagoon Nebula and is about a third of the size of the full moon in the sky which makes it about 15 light years in size at its distance,  Both are found low in the SW summer sky toward the center of the Milky Way. The gas in the clouds of NGC 6559, mainly hydrogen, is the raw material for star formation. When a region inside this nebula gathers enough matter, it starts to collapse under its own gravity. The center of the cloud grows ever denser and hotter, until thermonuclear fusion begins and a star is born. The hydrogen atoms combine to form helium atoms, releasing energy that makes the star shine. These brilliant hot young stars born out of the cloud energize the hydrogen gas still present around them in the nebula. The gas then re-emits this energy, producing the glowing arc-like red cloud seen near the left center of the image. This object is known as an emission nebula.      The  bluish area left of the red emission nebula shows the light from the recently formed stars being scattered — reflected in many different directions — by the microscopic particles in the nebula. Known to astronomers as a reflection nebula, this type of object usually appears blue because the scattering is more efficient for these shorter wavelengths of light. In the center of the image are dark snake like clouds of dark dust that block any light and are a third type of nebula found here in addition to the emission and reflection nebulas.  Unlike many of my images of nebulas this image is in true color and is a combination of 55 images taken over 20 hours.