Deep in the heart of the Lagoon Nebula (Messier 8) lies the bright Hourglass Nebula which is a distinctly shaped patch of nebulosity framed by tornado-like structures half a light-year in length. The star immediately to the left of the Hourglass is Herschel 36 which is thought to be responsible for most of the illumination in the area. The strong stellar winds are tearing the molecular clouds apart and is it believed that the difference in temperature between the hot surface of the clouds and their cold interior, combined with the pressure from the stellar winds is producing strong horizontal shear which twists the clouds into tornado-like shapes. The most prominent of these twisters visible in the Hubble image form the top edge of the hourglass and it can clearly be seen in the above image which is a stack of 136 exposures of 10.5 seconds each. Also visible throughout the image are many of the newborn stars that light up the rest of the Lagoon Nebula.