how do you use interplanetary missiles?

Go into the galaxy view page. There should be a missile button along where the pm/esp buttons are.

first you have to have a missile silo of 4 or more. Then you go into your defense page and make them. You can make up to 5 IPM per level of your missile silo, minus any space taken up by ABM's. Then go into Galaxy view and IF you are in range of the target,there will be an icon on the right side of the page.

To determine your range....Impulse drive x 5 -1, I say -1 because 1 is your planets galaxy, so if you have an Impulse drive of 5, you can reach 25 systems away starting with YOUR galaxy. So if you are in Galaxy 200 you can reach to gal 224 with an impulse of 5. (5x5-1=24)

ok thanks for the info