One big reason that life on Earth exists - Elise Cutts

4.5 billion years ago, Earth had barely even formed when it was struck by a rock the size of Mars, flying roughly nine kilometers a second.

The force of this collision partially vaporized both celestial bodies, temporarily turning the Earth's surface into an ocean of molten magma.

Today, some scientists call this cosmic crash the Big Whack.

And while our planet has long since cooled off, we’re still dealing with the impacts of this impact.

Not only did the Earth’s moon form from Big Whack debris, this collision quite literally knocked our world off-kilter.

Like practically everything in our solar system, the Earth is constantly spinning, and anything that spins does so around a line called an axis.

Earth's axis runs between the planet's poles, and our globe completes a rotation around it once a day.

However, instead of standing straight up, the Earth does all this at an angle of about 23.5°.