Sunday, September 09, 2007

Article: Total eclipse of the moon

Lunar eclipse during initial partial phase

Seems like everyone is always complaining about how hot it is in Texas during the summer. But that’s one of the things I love about Texas, especially the summer nights. What could be better than standing in the warm night air and drinking in the star light? Central Texas is great for amateur astronomers.

Actually, I’m kind-of lying, the warm air is not really that great for astronomers. Cool air holds less water and is therefore clearer than warm air and better for stargazing. However if, like me, you are not willing to stand outside in the cold, then it doesn’t matter how clear cold air is. That is what makes Central Texas summers perfect for people like me.

I was standing outside in the warm, moist morning air at 4:30 Tuesday morning to view the total lunar eclipse. I had my camera propped up on some pillows on my husband’s car since I wasn’t able to find a working tripod. The horses were out for the night and had nothing better to do then poke me with their muzzles to see if food would appear. And slowly the moon disappeared. The horses were completely unimpressed.

A lunar eclipse occurs when the shadow of the Earth falls on the surface of the moon. Since the moon is visible to half the world at any time, it’s about the easiest celestial event to witness. As the shadow moves, the bright face of the full moon gradually darkens. When you think about it, that’s amazing. You can actually view the relative movements of the Earth and Moon.

Looking closely as the eclipse progressed, I noticed that the boundary between light and dark was not a clean, sharp line. This fuzziness provided a mental contrast with memories of stark images from lunar landings. Even though I understood the phenomenon was due to diffusion of sunlight passing through the Earth’s atmosphere, it was still surprising to see.

Gradually, the entire moon fell into shade and the full glory of the eclipse manifested. The shadow of the Earth is not completely black. Some sunlight is scattered as it passes through the thin veil of the Earth’s atmosphere. If viewed from the moon, the Earth would appear to be ringed in fire, the red-orange color of infinite sunsets and sunrises. That diffused light falls on the darkened moon making it shine a dim but beautiful firebrick red.

The next lunar eclipse that will be visible in the United States is in February of 2008. Since the sun and the moon are on opposite sides of the Earth every month during the full moon, you might wonder why there isn’t an eclipse every month. This is because the orbit of the moon does not lie exactly in the plane of the Earth’s orbit around the sun, it’s about five degrees off. This is just enough to cause the moon to slide above or below the Earth’s shadow during most full moons.

One of the great sites of the internet is space.com. There’s a wealth of information there for anyone interested in astronomy. Go to http://www.space.com/imageoftheday/image_of_day_070829.html for some excellent images from this week’s eclipse. Another good site is www.MrEclipse.com. That site includes tables showing when and where to expect both lunar and solar eclipses and tips for photographing eclipses. None of the tips includes using pillows, pushing horses out of the way or living somewhere where the night air is like a warm blanket rather than a slap in the face. Obviously the tip section could use some expansion.

Photo: Lunar eclipse during totality.

1 comment:

kayla said...

this is so cool