Until now, scientists didn’t know for sure where most of the stuff around us came from. Now, they do.
By Rafi Letzter | SPACE.com
Silica, or silicon dioxide (SiO2), is just about the most abundant thing here on the outer shell of Earth. It makes up most of the planet’s crust by mass — about 60 percent, according to NASA. It’s the main thing in sand at the beach. It’s common in dirt and clay. It makes up most of the stuff in sandstone and quartz, and it’s a critical ingredient in feldspar (a super common sort of rock). Granite has a lot of it. Humans mix it into cement and melt it into glass. It’s also one of the more common molecules in the universe. And until recently, scientists had some good theories as to where it came from, but they weren’t sure.
Now, according to NASA, they know: All this silica around us was born in supernovas that ripped apart „AGB stars“ — a technical term for stars that, more or less, resemble our sun. [Gorgeous Photos of Granite]
A team of NASA researchers published a paper in the journal Monthly Notices of the Royal Astronomical SocietyOct. 24 that revealed the results of observations of two clouds of matter left behind after AGB supernovas: Cassiopeia A and G54.1+0.3.
Astronomers study the chemical composition of faraway things by carefully parsing the wavelengths of light emitted by those objects. Water causes one pattern of wavelengths. Gold another. And silica yet another.