traveling bright white light spotted over las vegas

What appeared to be a Jet Liner flying high up in the atmosphere turned into a bright burst of light. It started as a faint glow and got brighter than any star in the sky and suddenly flared up into a bright white light and, just as it appeared it resceded to a faint glow and, I could hardly make out the object only for a couple seconds. Like I said it was far away. I'm thinking, and it's only a guess, but, 50 miles away from me. It was traveling straight and away from me. I've seen shooting stars and this definately was not a shooting star, there was no tail. It had no blinking lights to make it out to be a jet liner. It was real interesting to see.