“Red Sky” is episode five of season five of Stargate SG-1.
SG-1 exit a wormhole at high velocity, just like they did in the first few episodes. Apparently, the adjustments they made for planetary shift stopped that from happening. I don’t think that was ever explained before.
The people of the world they arrive on are followers of the Asgard. They believe that SG-1 are elves (in the Norse sense of the word rather than the Tolkien one; I suppose Alf would be a better name). Shortly afterwards, the sun dims and turns red, and the ‘elves’ are blamed. Red sky all the time – not a good omen.
Carter thinks that their wormhole passed through the sun, destabilising it, because SGC removed some of the gate’s normal safety protocols. Not the easiest think to fix, a broken star. Not normally the easiest thing to cause, either, with the current technological level of Earth. Just shows how much damage you can do messing around with advanced technology that you don’t completely understand (although the Ancients later prove to have been pretty inept with technology they actually created).