Is Earth’s Core Like an Onion?

Earthquake waves traveling through Earth's center behave strangely—moving 3 to 4 percent faster when parallel to our planet's rotation axis than when crossing the equatorial plane. This puzzling phenomenon has intrigued scientists for decades, but new research suggests Earth's inner core may have its own layers, like an onion within an onion.

University of Münster geochemist Carmen Sanchez-Valle led a team that recreated the extreme conditions found 3,200 miles beneath our feet using diamond anvils that compressed iron alloy samples to about 1 million times atmospheric pressure while heating them to 1500 degrees Fahrenheit.

Their findings reveal that deeper into Earth's core, the percentage of iron increases while silicon and carbon decrease, creating distinct layers with different properties. These onion-like layers may explain why seismic waves behave so unusually as they journey through our planet's center, suggesting Earth's complexity continues surprising us even after 4.5 billion years.