Astronomy Picture of the Day

Explanation: When stars form, pandemonium reigns. A particularly colourful case is the star forming region Simeis 188 which houses an unusual and bright cloud arc catalogued as NGC 6559. Visible above are red glowing emission nebulae of hydrogen, blue reflection nebulae of dust, dark absorption nebulae of dust, and the stars that formed from them. The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace. And then they explode. The resulting morass can be as beautiful as it is complex. After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a naked open cluster of stars. Simeis 188 is located about 4,000 light years away and can be found about one degree northeast of M8, the Lagoon Nebula.