National Geographic

VOICES Voices Icon Ideas and Insight From Explorers

Menu

Ich Liebe Planeten

Germany takes on the worlds this week, as the 3rd European Planetary Science Congress gets underway in Münster.

Today’s cornucopia included a presentation from Gerhard Schmidt of the University of Mainz, who says that platinum rings come from outer space.

More precisely, the idea is that platinum, gold, and other precious “iron-loving” metals were stripped from the planet’s superheated self as Earth formed, but then were delivered back to the exterior layers by asteroid impacts once things cooled down a bit.

asteroid-jewel.jpg

The stony asteroid Kleopatra

—courtesy NASA

Schmidt was prompted to investigate the matter because the ratios of iron-loving metals in Earth’s mantle are not quite in line with their abundances in meteorites known as chondrites—stony chunks of space rock thought to represent pristine material from the birth of the solar system.

His team calculates that 160 asteroids each about 12 miles (20 kilometers) across smashed into Earth roughly 20 to 30 million years after the core formed, depositing the metals in question onto our young planet.

The glitch with this theory is that even after 12 years of studying impact craters on Earth, along with bits of earthly, lunar, and Martian rock from impact sites, Schmidt and co. can’t exactly match any known meteorites to the metal ratios found in Earth’s mantle.

What’s more, asteroids that might have the necessary ratios are predicted to come from the space between Mercury and Venus, but no known meteorites from this region have ever been found.

Still, it’s an intriguing hypothesis, especially for someone like me who is always looking for the next geeky but decorative conversation piece.