Morning Mercury 
By most standards, the planet Mercury is a bit of an afterthought. It never strays very far from the Sun in our sky, so it's hard to see. Only two spacecraft have visited the planet. And most ancient cultures awarded it second-class status at best.
It's easy to see why if you look for Mercury the next few days. It's farthest from the Sun for its current morning appearance, and it looks like a bright star. Even so, it's still quite low in the east at first light, so it's tough to spot through the clutter along the horizon and the waxing twilight.
For the ancient Maya of Mexico and Central America, the most important astronomical object was the planet Venus. They plotted its motions with great care. They built temples and observatories to align with its rising and setting. They even timed wars and royal successions to coincide with its comings and goings.
But they also kept an eye on Mercury. Its motions were recorded in the Dresden Codex, a collection of papers that contains much of our knowledge of Mayan astronomy. It shows that they recorded Mercury's position in the morning sky in the year 733 BC -- not far, in fact, from where it appears right now.
From their observations, Mayan astronomers calculated that Mercury rises and sets at the same spot on the horizon every six years and a few days. So even though Mercury wasn't one of their most important celestial objects, they paid close attention to it just the same.
Script by Damond Benningfield, Copyright 2010