NGC 1788, Reflection Nebula in Orion

NGC 1788, Reflection Nebula in Orion This is an unusual reflection nebula in that only the center is actually reflecting light and is blue in color and the rest of the nebula is surrounded by Hydrogen gas emitting red light. The nebula has a balance of interstellar dust and gas residing northeast of Rigel in the nebula rich constellation of Orion. This image of NGC 1788 is in true color with the blue color coming from light that is reflected off of dust in the nebula. This  light largely comes from Rigel, the brightest star in Orion . Crowning the top of the nebula is reddish light coming from Hydrogen gas emission which is excited also by light from Rigel. In this case the ultraviolet light excites  the Hydrogen gas and elevates it to an upper energy level. The reddish light at 655 nm  is emitted as the has returns to its ground state.  Strong winds from Orion’s bright stars have also shaped NGC 1788, and likely triggered the formation of the young stars within. NGC 1788 is 1300 light years distant and the field of view of the image is slightly larger than a full moon. At that distance the nebula is 13 light years across. The image is a combination of 106 images taken through broadband clear and RGB filters and a narrowband atomic filter capturing emission from Hydrogen gas.