UFO In Las Vegas?

I'm not a big believer of UFO's though i think there is someone else there but I can't explain what I saw tonight.
I was at the park in Henderson, by Horizon and Horizon Ridge and it is under the flight path of planes that go from west then do a turn and then go east and land at McCarren Airport.
Well, I was watching the planes from the dog park and was watching a Southwest jet going east before it started to turn.  Right after that jet passed, another object came from the southwest and was at a much higher elevation than the landing route but appeared lower than then the high altitude.  My son and I watched it, joking it maybe a UFO.  The object was not in the shape of a airplane but looked somewhat round.  The light was different than any landing light I have ever seen before.  The object was heading toward the Las Vegas Valley fairly fast, like a jet but not super fast
And then the light just disappeared.
And no, I was not drinking, not that crazy and my son saw the same thing.
By coincidence, President Obama was in town.
I blame Romney.