A New Moon is rising in the next few days, giving us a chance to bathe in the Earthshine, the light from the Earth that illuminates the Moon. Earth shines bright for the Moon, and the Moon shines for the Earth, but what's the shiniest thing in the solar system?
Right now is the perfect time to look for Earthshine. When the Moon is new, just a little bit of it is positioned so the sunlight hits it and bounces down to Earth. A lot of the Moon, however, is positioned just right for the light from the sun to hit the Earth, bounce to the Moon, and come back down to the Earth again. That's why we see, "The Old Moon in the New Moon's arms." The rest of the moon is visible next to the bright glowing crescent. The best time to see it is just around sunset for a New Moon that's growing, and just around sunrise is the best time for the waning crescent Moon. That's when the reflected Earthshine is brightest.
But Earthshine is never very bright. Albedo, the more general and less poetic name for the amount of light a celestial body reflects, is low for the Earth. Although it varies depending on how much cloud cover there is - clouds reflect far more light than ocean or land - Earth reflects only about 0.36 percent of the light that comes in. The Moon, though it's close by, isn't all that good at reflecting light either. Venus gives off a pretty good seventy percent. But the shiniest object in the solar system by far is Enceladus. This small moon of Saturn, only a hundred and sixty miles across and able to snug itself into the Gulf of Mexico, gives back a stunning 99 percent of what shines on it. Since it is covered with ice and water, it reflects nearly everything.
Although I don't wish to seem ungrateful for what we have in our neck of the woods, I can't help but wishing, just a bit, that our Moon was also covered with ice the way Enceladus is. Not only would we have been likely to find extraterrestrial life nearby, think of the incredible moonlit nights we would have had! Forget romance, we would have been able read all night long, and the world would be far more advanced.
Plus I've always wanted to see astronauts ice skating.
Top Image: Claude Schneider
Alternate Top Image(Purple): ESO/B. Tafreshi/TWAN
Enceladus Image: NASA