It's been 47 years since we made our 1st footprints on the moon - here's what you might not know about Earth's dusty companion

It's one of the most defining moments in American history: On July 21, 1969, Neil Armstrong became the first person ever to walk on the moon, taking what he called "one small step for a man and one giant leap for mankind."

Forty-seven years later, we're still learning new things about Earth's dusty companion. And some of the things that we do know about it are pretty mindblowing.

Here are a few facts about the moon that you might not know.