New Moon
Living on the Moon would be harsh. There's no air, the temperatures range from extreme heat to extreme cold, and lunar dust would get into every nook and cranny of a moonbase. But there would be at least one treat that you couldn't experience anywhere else: a full Earth hanging in the night sky.
In fact, there's a full Earth today. That's because the Moon is new. It's crossing the line between Earth and the Sun, so it's lost in the Sun's glare. It'll return to view as a thin crescent in the west in early evening in a day or two.
At new Moon, it's nighttime for the lunar hemisphere that faces Earth. But as seen from the Moon, Earth is in full daylight, so it casts a lot of light across the lunar landscape. Earth covers about 13 and a half times as much area as the full Moon does as seen from Earth. And on average, every square mile of Earth reflects between three and four times as much sunlight back into space as the same area on the Moon. When you put the numbers together, it means that a full Earth is about 40 times brighter than a full Moon.
To make it even more interesting, from any given point on the Moon, Earth appears to stand in the same position in the sky all the time; it doesn't rise or set, it just hovers in the same spot. So as the hours passed, you'd see different portions of Earth rotate into view. And as the days passed, you'd see Earth go through its own cycle of phases. That includes new Earth -- when the Moon is full.
Script by Damond Benningfield, Copyright 2006
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
|
Contact | About | Friends of McDonald | Sign up for Sky Tips
