I had though about this before but the recent Cosmos arc got me thinking again. We all remember one of the main plots in Stargate (1994) was that Daniel assumed that someone would have left instructions on the other side on how to get back (an address). As geeks and students of Sagan we know it isn’t so simple. Every planet they travel to would have a completely different set of constellations and point of origin. I never remember it being brought up in an episode and the more I think about it the more skeptical I am that they could have really made gate travel work so well.
I always assumed that it could be explained as one of those things the MALP was assigned to do as they scouted the planet. It could take photos at night and send them back to be analyzed. The problem is that it would only see half the sky. Even if it did get all the sky, how complex would the computer have to be to calculate where the Earth was and match the constellations?
Another thing is now with SGU, how does their gate work? We saw them stop at a star to dial out but the design is so different I hope they spend some time explaining it.