Sci­en­tists find an­cient dust that formed Earth

USA TODAY International Edition - - FRONT PAGE - Doyle Rice

Sci­en­tists have dis­cov­ered some of the orig­i­nal in­ter­stel­lar dust that formed the Earth and the so­lar sys­tem bil­lions of years ago, a new study said.

The dis­cov­ery is the “sur­viv­ing preso­lar in­ter­stel­lar dust that formed the very build­ing blocks of plan­ets and stars,” said lead au­thor Hope Ishii of the Univer­sity of Hawaii at Manoa.

Re­searchers col­lected the dust from Earth’s up­per at­mos­phere, where it was likely de­posited from comets. As comets pass near the sun, they re­lease dust that can reach Earth’s or­bit and set­tle through the at­mos­phere, where it can be col­lected and stud­ied.

The “dust” is tiny glassy grains called GEMS, or glass em­bed­ded with metal and sul­fides — typ­i­cally less than 1/100th the thick­ness of a hu­man hair.

As­tro­physi­cist Ethan Siegel said “our naive picture of a disk that gets very hot, frag­ments, and cools to then form plan­ets may be hope­lessly over­sim­pli­fied. In­stead, we’ve learned that it may ac­tu­ally be cold, outer ma­te­rial that holds the key to our plan­e­tary back­yard.” Siegel, who was not part of the re­search, wrote about the study in Forbes.

The study was pub­lished Mon­day in the peer-re­viewed jour­nal Pro­ceed­ings of the Na­tional Academy of Sciences.

HOPE ISHII

An elec­tron mi­cro­graph of an in­ter­plan­e­tary dust par­ti­cle that likely came from a comet.

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