Answer:
   
   The established candle lighting times are based on the more temporate
   zones. For other zones, the Rabbis came up with a solution: use the
   established time for lighting candle currently employed in the largest
   city to your south (or north, if you are in the antartic... or your
   hometown, if you are in space) where it is possible to set up proper
   candle lighting charts.
   
   Why is this? The idea of sanctifying Sabbath lights dates back to the
   Karaite controversy of the Eighth Century CE. In the controversy, a
   group of schismatics, led by Anan ben David, rejected the efficacy of
   the Oral Tradition, sticking to a literal interpretation of Torah. For
   example, when Torah said that one should not kindle fire in one's
   habitation on Shabbat, the Karaites disallowed any flame at all, even
   one kindled beefore the Sabbath. In response, the Rabbanites declared
   that not only was it permissible to light candles before Sabbath and
   let them burn, they even instituted rules and regulations -- and even
   a blessing -- for their kindling in every Jewish home. And thus was
   the lighting of Shabbat candles "born".
   
   So what are we doing when we kindle these lights? We are separating a
   period of time and consecrating it to spiritual purpose. Thus, while
   some might focus on the exact time, others focus on the
   sanctification.