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A view along the Milky Way reveals many billions of stars. The dark dust lane that is silhouetted against the stars provides the raw material for new star formation.
Stars are born inside these dark nebulae. Stars are not born in isolation but in groups. The energy unleashed from their birth bursts out the side of the dark nebula, making a glowing emission nebula.
▲ Star Cocoon
A cocoon is the protective shell from which a butterfly will emerge. Stars sometimes form inside cocoons, but they are cocoons of dust and gas. A Bok globule (above) is a dark cloud of dense dust and gas in which star formation sometimes takes place. These globules are named after Dutch astronomer Bart Bok, who discovered them in the 1940s. A typical Bok globule is trillions of miles in diameter and contains enough gas to make about a dozen stars like our Sun. Not all Bok globules will form stars. Some break up before they can collapse to form stars.
▲ Pillars of Creation
At first, this picture looks like elephant trunks, coral, or even enchanted castles. But these dark pillarlike structures are actually columns of cool hydrogen gas and dust. They are incubators for new stars. The pillars stick out of the interior wall of a dark nebula, like stalagmites from the floor of a cavern.
▲ Infrared Vision
Astronomers can look inside the Eagle Nebula pillars with infrared, light-sensitive telescopes. Infrared photographs show the entire network of turbulent clouds and newborn stars. Towers of cool gas and interstellar dust look green. These towers include the three famous Pillars of Creation. Red represents hotter dust, which is warmed by the explosion of a massive star about 9,000 years ago.
Carina Nebula
This is the largest star-birth region that can be seen in our galaxy. The fantasy-like landscape of glowing gases is sculpted by different forces. Among those forces are blistering ultraviolet radiation and the intense pressure of starlight from hot, blinding stars. They also include blasts from supernova (dying star) explosions.
◀ Giant Star Factory
Here, in nebula NGC 604, new stars are being born in a spiral arm of a galaxy beyond our Milky Way. Though nebulae are common in galaxies, this one is particularly large. It is nearly 1,500 light-years across! At its heart are over 200 hot stars that heat and light up the gaseous walls of the nebula, like searchlights hitting clouds.
Superbubble
This expanding bubble of hot gas shows the triggering of star formation. Very hot stars near the center of the bubble caused the bubble to expand into the cooler interstellar gas and dust around it. This expansion collectively compressed the gas. That ignited the formation of new star groups along the edge of the bubble. As a result, a superbubble formed, which is 70 light-years across. ▶
