Scientists have caught a handful of ghost particles escaping from deep inside Earth, leaving experts to wonder: What if our planet’s interior isn’t as evenly mixed as we thought? The particles, called geoneutrinos, were detected at a laboratory buried more than a mile underground in a Canadian mine.
By giving scientists a rare glimpse into the radioactive decay that keeps Earth’s core hot and moving, these new readings hint that radioactive material might be concentrated in some parts of the planet more than others. If future measurements confirm that, scientists may need to rethink a long-standing assumption about what is happening beneath our feet.
Earth might not be mixing itself evenly
Earth’s mantle is the thick layer of hot, slowly churning rock between the crust and the core. For decades, scientists have generally expected this material to be mixed well enough that radioactive elements are distributed relatively evenly throughout it. It is like a giant pot of soup slowly stirring itself. Given enough time, you’d expect the ingredients to spread around rather than remain clumped in one corner. But Earth may be more complicated than that.
Radioactive elements release heat as they decay, helping drive the slow movement of rock deep underground. That movement plays a role in the geological activity that shapes our planet, including the processes behind volcanoes and earthquakes. Earth’s internal heat also contributes to the dynamics of its magnetic field, which helps shield us from harmful charged particles coming from space. If radioactive material is unevenly distributed, some regions of the mantle could generate more heat than others.
Mark Chen, a particle astrophysicist at Queen’s University, told Quanta Magazine that the results could offer a hint that the mantle isn’t uniform. He suggested that deep structures inside Earth might concentrate certain elements. That is a big possibility, especially because scientists already know of two enormous, mysterious regions deep in the mantle near the core: one beneath Africa and another beneath the Pacific Ocean. Whether those structures are connected to the new findings remains an open question.
The particles are almost impossible to catch
Geoneutrinos are neutrinos produced by radioactive decay inside Earth. They are sometimes described as ghost particles because they barely interact with ordinary matter. Trillions of neutrinos pass through your body every second, and most travel straight through Earth without stopping. Detecting the tiny fraction that interact with a detector is an entirely different challenge.
The underground laboratory reportedly detected around 50 geoneutrinos last November, marking the first such detection in the Western Hemisphere. Before that, the only successful detections had come from experiments in Japan in 2005 and Italy in 2009.
Which side of Earth has more radioactive material?
The three experiments reported different signal levels. Italy’s reading was high, Japan’s was low, and Canada’s landed somewhere in between, according to Quanta Magazine. Taken at face value, those differences could suggest that the Western Hemisphere contains more radioactive material than the Eastern Hemisphere.
Geochemist William McDonough of the Chinese Academy of Sciences is not ready to make that call. He has cautioned that the estimates come with uncertainties, leaving scientists to question whether the differences reflect Earth’s actual composition or limitations in the measurements.
China’s next big experiment could help settle it
A massive new neutrino detector in China is expected to report results that could help researchers compare measurements and test whether the apparent differences hold up. More data will be crucial. With so few geoneutrinos detected so far, scientists need better measurements before they can confidently map how radioactive elements are distributed deep inside Earth.
Source: New York Post