Here is the full list of all 25 Interplanetary achievements.
Defeat two enemy planets in one turn.
Build 200 buildings on your planet.
Win 5 online multiplayer matches.
Produce 7,000 Energy in one turn.
Have 25,000 material in stock.
Fire Solar Laser superweapon.
Win an online multiplayer match with at least two players.
Win an online multiplayer match.
Fire Asteroid Diversion superweapon.
Defeat an enemy planet.
Win 10 online multiplayer matches.
Win 50 online multiplayer matches.
Win 100 online multiplayer matches.
Win 10 single player games.
Win 100 single player games.
Beat the Impossible AI.
Win an online multiplayer match with at least four players.
Win an online multiplayer match with eight players.
Destroy 100 cities over any number of games.
Hit your own planet with a railgun.
Grow five cities to their maximum populations.
Win a match with barely any population left.
Unlock all technologies.
Fire all the superweapons during the same turn.
Have your planet run out of material.