It is the 43rd century and humanity occupies a substantial chunk of the Orion Spur, the small galactic arm in which Sol is located. Homo sapiens Terra has become Homo sapiens Galactica.
Following the invention of faster-than-light travel in 2530, the Great Hegira went from a trickle to a flood as human-occupied space expanded at an exponential clip. Over the centuries, rivalries grew, as did star system navies. When widespread war finally came, it raged across entire sectors.
Mass bombardments of enemy planets took their toll. Much that had been built during the preceding thousand years was smashed in flashes of nuclear fusion.
A dark age descended. Eventually, a new Pax Galactica took hold. The return of stability brought with it a renaissance. Much knowledge that had been lost was regained.
Much, but not all.
On worlds across human space, parents told their children stories of a place where once dwelt knights and princesses, magicians and dragons, where bold warriors sallied forth to victory or defeat.
What the children did not learn was where this magical place could be found. The years of chaos had robbed them of that information. The stellar coordinates of Sol were lost.
And with them, the location of Planet Earth.