M8 is located approximately 5,200 light years from Earth and is known as the Lagoon Nebula.  When Messier first cataloged the object he listed it as an open star cluster and only mentioned the nebula as surrounding the bright star, 9 Sagittarii.  The Lagoon Nebula contains collapsing dark clouds of dust and gas that are the birthplace for new stars.  Within the brightest part of the Lagoon is the feature called the Hourglass Nebula.  This nebula is named for its distinctly hourglass shape.  The Hourglass is in an active star formation region of the Lagoon.  Very hot young stars excite this bright emission nebula.  The primary illuminator of the Hourglass is the hot star Herschel 36, which appears just to its right.  Just to the left and slightly above the Hourglass is the brightest of the stars associated with the Lagoon Nebula, 9 Sagittarii.  A blue reflection nebula surrounds the star and the star's intense radiation is a major exciter of the Lagoon Nebula.

¹ http://www.seds.org/messier/m/m008.html