Sky watch: Moon puts on double feature in mid-January

It's funny how the sky can be such a great memory trigger.

I remember as a child racing home from school to watch "Superman" on television, as the comforting smells of my mom's cooking would waft through the house. It was such a thrill to see how this "visitor from another planet" would save our world each night.

But it was the ending credits that gave me the greatest thrill. With proud and majestic music, they showed behind the words planets and moons in crescent phases. They looked so real, mysterious and exciting at a time when travel to other worlds was merely a dream.

After the show, I'd often throw on a coat and run out to the backyard to watch the stars come out. Sometimes, I'd be surprised by a wonderful crescent moon hanging beautifully above the colorful sunset. It always appeared so delicate - so exquisite and three-dimensional.

, look at the moon and you'll see not only a sunlit crescent, but the ghostly image of its full disk. Few things in the heavens appear more three-dimensional than this; in fact, if you want a stunning 3-D experience, check it out with binoculars or a small telescope.

Why the moon's "dark side" becomes visible at these times was first explained by the 15th-century Italian artist and inventor Leonardo da Vinci.

He recognized that when the moon appears as a crescent in our sky, a hypothetical lunar astronomer would see in his sky a nearly full Earth. And, just as a bright moon illuminates the dark night on Earth, a bright Earth would illuminate even more the darkness of the moon. Today, we call this phenomenon earthshine.

Mark your calendars for Jan. 16 and 17. I know I'll be out watching this most beautiful of moons, as I relive those magical memories of childhood.