Dust Older Than the Sun Found in Earth's Atmosphere

April 28, 2009

Meteorites on the ground or icy comets millions of miles away are usually the only sources of ancient matter from the early days of the solar system.

But in a high-flying experiment, researchers have used a sort of chemical flypaper to scoop up comet dust from Earth's atmosphere—and it appears to be some of the oldest matter in our cosmic neighborhood.

The ancient specks, some of which are more than 4.5 billion years old, may support the theory that an exploding star helped trigger the birth of our sun.

The dust has survived in an unaltered state for so long because it got swept up during the formation of icy comets, researchers say.

"Comets are like refrigerators for this material," said study leader Henner Busemann, an astrophysicist at the University of Manchester in the U.K.

"They store this very pristine material, which never changes again."

Dust From the Sun's Nursery

Busemann and colleagues collected the particles in April 2003, as Earth spun through the dusty tail of comet 26P/Grigg-Skjellerup.

The team asked NASA to fly an airplane at about 12 miles (20 kilometers) up for several hours during the comet's visit, using instruments equipped with silicon oil to capture particles trapped in the upper atmosphere.

By comparing the dust to samples collected from comet-smashing probes such as Deep Impact and Stardust, the scientists were able to tell that the particles in Earth's atmosphere came from 26P/Grigg-Skjellerup.

(Related: "Stardust's Comet Clues Reveal Early Solar System.")

The team's analysis also shows that two of the grains have a unique chemical fingerprint linking them to the huge gas cloud scientists think was our sun's stellar nursery.

Also, one of the dust particles contains grains of material that match predictions for the types of matter expected to form in the cooling gas left over after a supernova explosion.

Scientists have speculated that shockwaves from a nearby supernova helped trigger the birth of our sun, and some of the comet material could have originated from that blast, Busemann said.

The astrophysicist presented his research last week at the European Week of Astronomy and Space Science conference at the University of Hertfordshire in the U.K.

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