A Caltech-led study suggests that two massive, iron-rich structures deep within Earth’s mantle are the remains of Theia, an ancient planet that collided with Earth, also creating the Moon. This discovery answers long-standing questions about the Moon’s origin and Theia’s fate. In the 1980s, geophysicists made a startling discovery: two continent-sized blobs of unusual material … Continue reading Earth’s Hidden Guests: Strange Blobs in Deep Mantle Are the Remains of an Ancient Planet