The summer Milky Way is a spectacular sight when seen from truly dark skies. It is an arcing swath of gray glow and shadow, comprised of an immense volume of stars, gas and dust. It is a sad state of affairs how the growing excess of nighttime city light has obscured our view of this amazing feature of our home in space. One of the most spectacular aspects of this sight are the nebula of core, giant regions of ionized Hydrogen gas glowing faintly, surrounded by countless billions of stars and intertwined with filaments of dark dust that frames curious shapes.
Originally discovered around 1654 (or possibly earlier) by astronomer Giovanni Hodierna, Lagoon Nebula is one of the very few nebula visible with the naked eye in North America. It appears as a faint blob of gray a short distance above the galactic core, at a distance of somewhere between 4000-6000 light years. Not quite as bright as another nebula visible to the naked eye, the Great Orion Nebula, it is larger at around 100 light years across. It is one of the more interesting objects when viewed through a pair of binoculars or a telescope, and appears to be oval shaped with a small open cluster of stars that look almost like the sparkle of specular highlights on the waters of a lagoon. Lagoon, though discovered earlier, is also a part of the Messier catalog, designated M8.
There are many interesting features of Lagoon nebula. The region is packed with a complexity of dazzling reflection, arcing and billowing emission and filamentary absorption or dark nebula. Hidden away in the shapes of the dust and gas, one can find the shape of a standing bear in the hydrogen gas near the upper right limb of the lagoon. Silhouetted against the blue reflections of the “sparkling pool” of the lagoon itself one may find the shape of a leaping whale, fins outstretched. The Lagoon nebula is also part of a larger structure, outlined by lanes of dark dust. Looking at the whole object, one may find something truly curious: a giant foot!
Lagoon is not the only nebula of the core, however. A short distance away, a smaller nebula, no less interesting, emits an interesting mix of blues and pinks. Comprised of stellar reflections (blue), Hydrogen (pink) ionized gasses, and molecular structures (the dark nebula), Trifid nebula is an interesting object. This object was also discovered by Charles Messier, designated M20. It’s name indicated the trifurcated or “three lobed” appearance of the core structure. Unlike Lagoon, Trifid is not a naked eye object, however it is easily visible with a pair of binoculars or a small telescope. Trifid is slightly smaller than Orion Nebula at ~20ly across. Within the core of Trifid, upon closer inspection, one may find a multitude of interesting lobed structures, jets and other strange shapes.
If you ever find yourself out away from cities and towns during the summer, along a rural road, or camping in the mountains, stop for a moment after the last light of the sun has faded. Turn off all light, and wait…and watch. Look for the big glowing blob in the sky, and then look closer for the smaller glowing blob near the center of the larger one. If you have a pair of binoculars, point them skyward, and see if you can find Trifid, and keep looking, as there are countless other objects up there…star clusters and other nebula. They are amazing sights!