Touchstone

The Touchstone is a device, that can control the weather on planetary scale. It is an artifact, found on PX7-941, where it is used by the Madronans to maintain the weather. It was left behind by an unknown alien culture, when they terraformed the planet roughly 900 years ago.

The Touchstone works on any planet, not only Madrona - SG-1 discovered this, when the Touchstone was stolen by the NID and experimented with. SG-1 uncovered this plot of the NID and returned the Touchstone to the Madronans.