This is a picture of columns of gas in the Eagle Nebula (sometimes called M16). They are areas of cool gas, which are what is left after millions of years of evaporation from a continuous cloud. As time goes on, these columns are slowly eroded by further evaporation.
As the columns slowly disappear, they reveal denser globules of gas, which are believed to be the birthplaces of stars, condensing from the gas.
This picture was taken in April, 1995 by the Hubble Space Telescope. It is not a true-color picture, but instead shows emission from atoms of sulfur, hydrogen, and oxygen.
PtyS 105 is the course that talks the most about nebulae and star formation.
PtyS 106 also deals with the subject somewhat, in the context of the birth of the sun and our own solar system.