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Astronomers trace humans' dusty origins

WASHINGTON - Astronomers have taken a baby step in trying to answer the cosmic question of where we come from.

Planets and much on them, including humans, come from dust — mostly from dying stars. But where did the dust that helped form those early stars come from?

A NASA telescope may have spotted one of the answers. It's in the wind bursting out of super-massive black holes.

The Spitzer Space Telescope identified large quantities of freshly made space dust in a quasar about 8 billion light years from here.

Astronomers used the telescope to break down the wavelengths of light in the quasar to figure out what was in the space dust.

They found signs of glass, sand, crystal, marble, rubies and sapphires, said Ciska Markwick-Kemper of the University of Manchester in England. She is the lead author of a study that will be published later this month in Astrophysical Journal Letters.

Dust is important in the cooling process to make stars, which are predominantly gas. The leftover dust tends to clump together to make planets, comets and asteroids, said astronomer Sarah Gallagher, a study co-author at the University of California Los Angeles.

"In the end, everything comes from space dust," Markwick-Kemper said. "It's putting all the pieces of the puzzle together to figure out where we came from."

Astronomers figure that the planets that formed in the past several billion years — and those away from quasars — came from dust that was belched from dying stars.

That's what happened with Earth.

That still leaves a question about where the dust from the first couple billion years of the universe came from, which helped form early generations of star systems.

"It's formed in the wind," of the black holes, Markwick-Kemper said. Gas molecules collide in the searing heat of the quasar, which is thousands of degrees Fahrenheit, and form clusters.

"These clusters grow bigger and bigger until you can call them dust grains," she said.

Scientists who weren't part of the study hailed the work.

Cornell University astronomer Dan Weedman, the former director of NASA's astrophysics division, said the study was an important step in answering a fundamental mystery of the early universe.

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