New Study Claims It’s Snowing—4,000 miles under the Earth

Samantha Liu '22

Since the beginnings of modern geology, science has accepted that the earth’s core is hot. Under immense pressure. Volcanic. But now, researchers claim that the earth’s inner core could be in a perpetual, bizarre winter wonderland, with crystal “snow” drifting down from the molten outer core. 


A study published in the Solid Earth Journal of Geophysical Research by scientists Youjun Zhang and Peter Nelson, describes these “snow” particles, which are actually formed from magma chambers in the molten outer core. Heat and pressure crystalize minerals from the melt and compact them into iron particles. The iron then falls, literally surrounding the inner core in 200-mile-thick piles of crystals suspended in water.


“It’s sort of a bizarre thing to think about,” co-author Nick Dygert notes. “You have crystals within the outer core snowing down onto the inner core over a distance of several hundred kilometers” [1]


The same iron snow theory was proposed earlier in the 1960’s, but according to what had been the contemporary geology knowledge, scientists had decided that it was impossible given the heat and pressure conditions. But newer data by lead researcher Youjun Zhang and other journals may actually substantiate this possibility of crystallization in the earth’s interior. 


Researchers of the study relied on seismic waves to image the core, generated by earthquakes and picked up in different stations across the world. They compared the paths of primary waves, which travel through both liquid and solid matter, to secondary waves, which can only travel through solid earth. Scientists witnessed some secondary waves definitively slow down around the western hemisphere’s outer core, then speed up again as they passed that region. Others just bounced back directly to the station. This aberration is key to the Zhang-Nelson study, who attribute it to the existence of this semi-liquid boundary. 


Given the importance of the earth’s core in natural phenomena, understanding its composition could help scientists understand larger geological processes, such as magnetism and the movement of tectonic plates. Bruce Buffet, geoscience professor at the University of California, Berkeley,says the research could introduce entirely new answers to questions about the Earth’s origins. “[It] allows us to draw inferences about the possible compositions of the liquid core, and maybe connect this information to the conditions that prevailed at the time the planet was formed. The starting condition is an important factor in Earth becoming the planet we know” [2].