Illustration comparing the planets of the Solar System and the Sun on the same scale. The planets are shown to scale relative to each other but their distances are not. From left to right the bodies ...

Approximately 4.5 billion years ago, a planet called Theia slammed into the Earth. The impact melted parts of Earth’s mantle and sent a massive cloud of debris into space. Over time, this debris came ...

LONDON — A long-lost planet that helped create the Moon may have formed much closer to the Sun than scientists once thought, according to new research. Scientists have discovered that Theia, the ...