The Lagoon nebula,which can be found about 5,000 light years from Earth, toward the constellation of Sagittarius, is one of the most memorable nebulae in this galaxy.. Perhaps this image helps explains the "why."Here, we stare straight into the heart of this stellar nursery, seeing various nebulae-driving-mechanisms at work.
First off, we see two gas clouds, each spanning approximately half a light-year in length, twisted into a funnel-like shape. Both of these clouds are the result of extreme stellar winds emanating primarily from one bright O-type central star, dubbed Herschel 36 (with some help from its neighbors, of course).
Encompassing it are a few other areas of interest, which notably include huge walls of red interstellar dust. The dense concentration of dust hides the light from stars that are buried inside of it, but incredibly, it also kick-starts an interesting chain of events, culminating with the formation of the funnels we see dominating the scene.
Despite being largely hidden from sight in a cool cradle of dust, the energy from these stars must go somewhere, thus it kind of pervades the medium in which it resides. This, in contrast to the ionizing radiation that heats up the gas clouds and causes them to glows, leads to drastically different temperature differences, potentially creating horizontal windshears that rip the region apart from the inside-out
Overall, this region extends about 5 light-year across and can be found about 5,000 light-years from Earth in the Sagittarius constellation.
Download a larger image here.