Why "L5"?

First - I should clear up a misconception - the station itself is called "Harmony 7" (because it has seven levels - logical right?).

L5 is the place Harmony 7 sits in space.

To understand why 'L5' we have to talk a bit about orbital mechanics...

WAIT! Come back! I promise it's gonna be ok.

The 'L' in L5 stands for 'Lagrange' (no, not the city in Texas from ZZ Top fame - that's 'La Grange') as in 'Lagrange point'. A Lagrange point is a place of gravitational balance for small(ish) objects between two really big objects in space - like the Earth and the Sun. Think of it as a gravitational safe zone where all the forces that are pushing and pulling on an object in space cancel each other out. That's a big deal because whatever you put at a Lagrange point will stay where you put it without using thrust to counteract gravity - sounds like a pretty good place for a space station right?

So why L5 and not L1 or L2 which are a lot closer to Earth and the Moon?

Stability! L1 and L2 are a lot closer, but they have a problem - a three body problem (trust me, that joke gets less funny the more you understand it), at L1 and L2 the moon causes the Lagrange points to move, no a lot, but enough to require periodic readjustment to our orbit - that needs energy and/or fuel to fix.

L3 has a similar issue because of the not quite circular orbit the Earth follows - oh and it's on the other side of the sun which makes getting messages, assistance, and take out from Earth a lot harder.

So why not L4?

Either one is stable and would be a great place for a space station, but L5 is safer for approaching ships from outside the solar system.

So there you have it - L5 is the best place to put a station for interstellar commerce, trade, travel, and diplomacy - we hope you'll come visit soon!