The Sol system is the solar system in which Earth is situated. All planets in our solar system are present as well as some moons. However, because of the endless multitude of systems, it might seem impossible to find one specific system. Fear not. For here is a guide to locating the planet itself!
The first thing you need to do is find out the galactic coordinates of your position. To do this hover your mouse over the little UFO icon at the bottom of the screen. This should produce a little box with Angle: XXX, Distance: XXX (pc). "Angle" is from 0-359 degrees, showing how far round the galactic core you are. "Distance" is your distance in parsecs from the Galactic Core. The location of the Sol System is:
When looking for this, remember that the arms of the galaxy curve. Try going to Angle 225.06 then zooming out and drawing an imaginary line from the core, through you and see where it crosses an arm about halfway down. That is where you are aiming for.
There are two achievements available to you. First is "Manifest Destiny" for finding the Earth. Simply enter the Earth's atmosphere to get it. The Second is "Oh The Humanity!". To do this you must use a planet buster on the Earth. What you can do though, is planet bus the Earth, but don't save. Then you can keep the achievement and the Earth.