If that's taken in the morning, it's Venus or Jupiter. They're in the same place in the sky right now, Venus is a bit brighter though.
If it was the theorized "Planet X" you wouldn't be able to see it. It supposed to be a small, rocky body just outside of the Kuiper belt. Large planets that are closer (specifically Uranus and Neptune) aren't visible, so the theorized PX wouldn't be either.