Do you want to explore edges of infinite space? Do you want to fly beyond everything you know? Or maybe build stations millions of units away from HOM? If so, you should know about some things.
If you traveled around 40,000 - 70,000 units from SOL, you may start to experience weak vibrations on your ship (this depends on how big the spacecraft is). It's noticable only on multi-module vehicles or the Station Builder Tug .
After you pass the 100,000 mark, shaking becomes more noticable. If you open cargo view, you will see items shaking.
At the 1,000,000 mark docking becomes hard, as ports are not displayed correctly. Fuel, power and cargo managment will become harder as well.
After 5,000,000 units have passed, direction pointers start to glitch, opening pressurised doors now takes multiple tries. Exhaust won't be coming from engines anymore.
Beyond 15,000,000 you're pretty much screwed. Direction pointers become unreadable, power, fuel, cargo and air become totally unmanagable. Thrusters, engines,and Oxygen Propulsion is still working as usual, so you can fly back home, assuming you can tell where you're going.
Several billion units out, the stars disappear. At 10 million the distance counter loops, meaning it shows not your true distance but your distance module is 10000000.
A way to see the actual distance from sol when it is over 10 million units is to head to the veichles sector and see your distance from sol.