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Looking along the Milky Way, you can see many billions of stars. The dark dust lane that is outlined against the stars provides the raw material for new stars.
Stars are born inside these dark nebulae. They are not born by themselves but in groups. The energy released from their birth bursts out the side of the dark nebula. It creates a glowing emission nebula.
▲ Star Cocoon
A cocoon is the protective shell in which a butterfly grows. Stars sometimes form inside cocoons, but they are made of dust and gas. A Bok globule (above) is a dark cloud of dense dust and gas. Star formation sometimes takes place inside it. 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. It 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 fairy castles. But these dark pillarlike shapes are actually columns of cool hydrogen gas and dust. They are places for growing new stars. The pillars stick out of the inside wall of a dark nebula. They sort of look like stalagmites on a cavern floor.
▲ Infrared Vision
Astronomers can look inside the Eagle Nebula pillars with infrared, light-sensitive telescopes. Infrared photographs show the whole network of stormy clouds and newborn stars. Towers of cool gas and interstellar dust look green. These towers include the three famous Pillars of Creation. Red shows areas of hotter dust. The dust was warmed by the explosion of a massive star about 9,000 years ago.
Carina Nebula
This is the largest star-birth area that can be seen in our galaxy. The landscape of glowing gases is shaped by different forces. Among them are ultraviolet radiation and the pressure of light from hot, blinding stars. The forces 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. Nebulae are common in galaxies, but this one is really big. It’s nearly 1,500 light-years wide! At its heart are over 200 hot stars. They heat and light up the gaseous walls of the nebula, like searchlights on clouds.
Superbubble
This expanding bubble of hot gas shows how star formation begins. There are very hot stars near the center of the bubble. They caused the bubble to expand into the cooler interstellar gas and dust around it. This expansion compressed the gas. That triggered the formation of new star groups along the edge of the bubble. As a result, a superbubble formed, which is 70 light-years wide. ▶
