The true age of the moon just became a little clearer. In a new study, scientists show how a massive "remelting event" may have reset the age of almost all lunar rocks, tricking scientists into thinking our planet's constant companion is younger than it is. However, the moon's exact birth date remains a mystery — and could elude us for a while yet.
The moon formed in the solar system's early days when a large protoplanet named Thea slammed into a baby version of Earth, creating the planet we know today and ejecting enormous masses of molten rock into space. The ejecta became trapped in orbit around Earth before cooling and condensing into the satellite that currently circles our planet roughly 239,000 miles (385,000 kilometers) away on average. Scientists initially believed this happened somewhere around 4.35 billion years ago, based on the age of lunar samples recovered during NASA's Apollo missions.
