Lagrangian Point

From Slackerpedia Galactica

Lagrangian points, also called Lagrange points, are like Switzerlands in the gravity between two objects (like a planet orbiting a star). At a Lagrangian point, the gravity between the two object cancels out like a tie in a game of Tug of War. There are five Lagrangian points in a two-object system. An object placed in a Lagrangian point could stay there like, forever. Lagrangian points are popular hangouts for space probes and small moons.

The Lagrangian points have really witty names. They're numbered one through five. For the Earth and the Sun, L1 is the one between the Earth and the Sun. L2 is the point on the far side of the Earth from the Sun. L3 is the point on the far side of the Sun from the Earth. L4 is about 60 degrees ahead of the Earth in it's orbit around the Sun. L5 is the point about 60 degrees behind the Earth in it's orbit around the Sun.

One idea for how the Moon formed is that an object about the size of Mars smacked into the Earth. Lots of stuff was launched into Earth orbit. Much of that came together and became the Moon.

Where did this object come from? One idea is that material gathered at either L4 or L5. It got larger and larger. Eventually, it got so large that it couldn't be considered a two body system anymore, and the orbit became unstable, crashing into the Earth.

Why does Venus spin backwards? One idea requires that two large objects hit it. Could it be from Venus's L4 and L5?