Normally, we measure distances in Astronomical Units, 1AU being equal to the distance between earth and the sun. As the game takes place within the solar system, a 1 or 2 digit number is not a good way of representing the distances a player is traveling in the normal gameplay.
1 AU = 149,597,870.691 km
149597870691 in meters
Therefore, by use of my amazing futuristic genius (by which I mean the application of 8th grade metric terminology), distances in this game ,will be measured in GigaMeters (Gm) or in terms of how many billion meters they are.
Even then, I will represent the distances within two decimals as well, just to have a bit more detail on screen.
Format 000.00
1 AU = 149.59 gm
This will be far more accurate and proportional to space. It is also easier to quantify in terms of actual gameplay, as opposed to having some stupid fictional or sci-fi measurement.
In other words, don't be this guy: