For this achievement, you need to visit all the planets in the Galene solar system.
You unlock Galene by first having $1 million Moolah at once, allowing you to fight the boss, then traveling to the Wormhole and purchasing access to Galene for $1 million Moolah.
The 7 planets included are the following:
Bloodbus Majoris
Bloodbus Minoris
Squibblius
Quelbrog
Quingron
Nigel
Saquanus
If you have the planet tracker, you can track the planets even before visiting them. If you have the distance upgrade, you can see how far they are from you at the time as well.
Don't forget to start building your empire when visiting, if you wish. As well as building an ATM satellite when possible so you don't have to return to collect your earnings.
Careful, the solar system is larger and the lock in fights are likely more difficult than in Sol.