For the first time ever, scientists have discovered some of the original interstellar dust that formed the Earth and the solar system some 4.6 billion years ago. The interstellar dust is estimated to be much older than the sun.
The international team of researchers, led by Hope Ishii from University of Hawaii at Manoa (UH Manoa), first collected the surviving ancient dust from Earth’s upper atmosphere and then studied the dust’s chemical composition using infrared light and electron microscopes at Berkeley Lab’s Advanced Light Source (ALS).
They found that the dust contains minute glass-like fragments called GEMS (glass with embedded metal and sulfides). GEMS, which are believed to originate from comets, are glassy tiny particles that are typically less than 1/100th the thickness of a human hair. Notably, when comets pass near the sun, they release dust that that settles in Earth’s orbit, which scientists are able to collect.
On analyzing the interstellar dust, scientists found that the initial solids from which the solar system formed consisted almost entirely of carbon, ices, and disordered (amorphous) silicate. The dust was mostly destroyed and reworked resulting in the formation of planets.
Dr Ishii said that the research team’s observations suggest that these exotic grains represent surviving pre-solar interstellar dust that formed the very building blocks of planets and stars.
The team found that these grains were originally fused together in a cold radiation-rich environment.
One of the researchers, Jim Ciston from the Lawrence Berkeley National Laboratory, said that the presence of specific types of organic carbon in both the inner and outer regions of the particles suggests the formation process occurred entirely at low temperatures.
“Therefore, these interplanetary dust particles survived from the time before the formation of the planetary bodies in the solar system, and provide insight into the chemistry of those ancient building blocks,” Ciston added.
The study was published in the peer-reviewed journal Proceedings of the National Academy of Sciences.