Planetary weapons?

[Billz]

Is there a way to give a select, normal planet, some kind of weapon that would fire on a ship when it is close enough (Example: Tollan Ion Cannon 'SG1- Pretense, Between Two Fires. Ancient weapon 'SG1 - Ascension. Defense satellite grid 'SG1- Absolute Power)?

[MLeo]

Only ships may have weapons.
But it's possible to fire a projectile from anywhere, toward any point.
Even if AI also require a ship.

But it's possible to have a planet ship, it's been used in some systems for things like cities.