Red Sky (S05E05)

After an unexpectedly rough ride through the Stargate, SG-1 emerges on an alien world known as K'Tau. There, they find a peaceful, agrarian people still worshipping the old Norse gods, evidence that this is a protected planet of the Asgard. Elrad, their religious leader, welcomes SG-1, believing them to be elves sent by their God Freyr. But Malchus, another acolyte in the church, thinks they are the harbingers of evil and is rather vocal about his views. But soon after their arrival, the sunlight mysteriously shifts and the sky becomes increasingly red. The people of K'Tau take this as a sign from the Gods. But upon closer examination, Carter discovers that the light frequency of the sun is shifting toward the infrared end of the color spectrum. The wormhole they created to travel to this planet caused the solar reaction to change and SG-1 may well be responsible for the impending death of this planet. O'Neill appeals to the Asgard for help, but they refuse to become involved. Now, SG-1 must solve a planetary problem that may very well be beyond their technological abilities. (Metro-Goldwyn-Mayer (MGM))