Astronomers are essentially pretending to be detectives when they observe the Solar System. We examine every item in the universe, including planets, moons, asteroids, and comets. By examining them, scientists can glean hints that describe the Solar System's early history.

There is proof of what scientists refer to as 'massive collisions' all around the Solar System. Why does that matter? It seems that planet creation was REALLY violent during its latter stages. There were numerous planet-sized objects floating around, and they frequently collided with one another.

When two objects the size of planets collide, the impact is truly catastrophic and is more than enough to shatter an entire globe. Exactly that is what we believe happened to the planet Mercury.

All the evidence points to Mercury being twice as large as it is now when it formed. But long ago, not long after Mercury originated, it collided with another object of similar size, nearly destroying Mercury in the process.

Large portions of Mercury were destroyed in the collision, leaving only the metal core and a thin layer of debris on top. We can still see the wounds left by a collision that tore a planet apart four billion years ago (that's 4,000,000,000 years).

Our own planet, Earth, is the most well-known example of a planet being pulled apart. You see, astronomers believe that Earth formed independently. Today, however, we can see that Earth has a companion in the form of the Moon. So, from where did the Moon originate?

Earth collided with another planet not long after it spontaneously formed. That planet, dubbed 'Theia' by astronomers, was roughly the size of Mars and collided with us fairly softly (as collisions between planets go).

However, even a minor planet-to-planet collision can be incredibly catastrophic. Any life that may have emerged at that time would have perished since the collision would have converted the entire Earth into molten rock. It would have destroyed Theia and tore Earth apart.

Theia's and Earth's debris would have sprayed into the area surrounding our planet. Because Earth's gravity was so strong, the majority of the debris was confined and eventually came together to form the Moon.

You can tell everyone that the Moon is a reminder of a massive collision that occurred when Earth was young anytime you look up at it in the sky. Because Earth was once actually destroyed in a collision with another planet.