One big reason that life on Earth exists

Explore the Big Whack theory, and how the event could have created the Moon and given Earth its all-important axial tilt.

--

4.5 billion years ago, Earth was struck by a rock the size of Mars flying 9 kilometers a second. The force of this collision temporarily turned Earth’s surface into an ocean of molten magma. Today, some scientists call this cosmic crash the Big Whack, and we’re still dealing with the impacts of this impact. Elise Cutts explores the pivotal role Earth’s obliquity plays in