Coeur de la nebula de la Lagoon dans le sagittarius/HST - This NASA Hubble Space...

Coeur de la nebula de la Lagoon dans le sagittarius/HST - This NASA Hubble Space Telescope (HST) image reveals a pair of one - half light - year long interstellar “” twisters”” in the heart of the Lagoon Nebula (Messier 8) which lies 5,000 light - years away in the direction of the constellation Sagittarius. The central hot O type star, Herschel 36 (lower right), is the primary source of the ionizing radiation for the brightest region in the nebula, called the Hourglass. Other hot stars, also present in the nebula, are ionizing the extended optical nebulosity. The ionizing radiation induces photo - evaporation of the surfaces of the clouds and drives away violent stellar winds tearing into the cool clouds. Analogous to the spectacular phenomena of Earth tornadoes, the large difference in temperature between the hot surface and cold interior of the clouds, combined with the pressure of starlight, may produce strong horizontal shear to twist the clouds into their tornado - like appearance. These color - coded images are the combination of individual exposures taken in July and September, 1995 with Hubble's Wide Field and Planetary Camera 2 (WFPC2) through three narrow - band filters (red light - - ionized sulphur atoms, blue light - - double ionized oxygen atoms, green light - - ionized hydrogen)