NASA's Hubble Confirms that Galaxies Are the Ultimate Recyclers

Galaxies learned to "go green" early in the history of the universe, continuously recycling immense volumes of hydrogen gas and heavy elements to build successive generations of stars stretching over billions of years. In other words they are more fuel efficient than any hybrid car on the road. This ongoing recycling keeps galaxies from emptying their "fuel tanks" and therefore stretches out their star-forming epoch to over 10 billion years. The catch is that those galaxies that crank up the rate of star formation can blow away their remaining fuel, essentially turning off further star-birth activity. But galaxies like our Milky Way that frugally pace the rate of star birth can go on building new stars at least one billion years into the future. /HUBBLE SITE