Episode 57 of "Stargate-SG1"
s03e13 The Devil You Know (2/2)

The Tok'ra find out Sokar is going to take his ship in orbit around Netu, and come up with a plan to kill him: since they don't have any weapon capable of penetrating Sokar's shields, they are going to launch some kind of nuclear device into the core of Netu. There it will build up critical mass, and the planet will explode, along with Sokar and his ship. The device gets launched, but Jack, Daniel, Sam, her dad, and Martouf are still on the planet. They now have 12 minutes to get off of the planet, but first they have to deal with an old enemy...