Seeing the dark side of the moon
By Robinson Duffy
rduffy@newsminer.com
Published August 27, 2007
The Earths shadow, cast by the sun, will blot out the moon early Tuesday morning during the first total lunar eclipse visible from Fairbanks since 2004.
It looks like well have a grandstand seat for it, because Alaska will be one of the few parts of the United States to see the (full) eclipse, Bob Fischer, a lead forecaster at the National Weather Service in Fairbanks, said.
The ecliptic dance, with the moon, Earth and sun briefly falling into line, will begin at around 1 a.m. Tuesday. The moon will be nearly due south and appear high in the Fairbanks sky, according to Martin Gutoski with the Fairbanks Astronomical Unit. By 2 a.m., the moon will be fully engulfed in the Earths shadow and will appear a ruddy copper color.
If theres more dust and smoke in the atmosphere it turns red or a real blood red, Gutoski said of the eclipsed moon.
The moon, which does not produce any of its own light, but rather reflects the suns light down to Earth, doesnt completely disappear even when its fully within the Earths shadow. Gutoski said thats because a small portion of the Suns light bends around the Earths atmosphere.
You get refraction around our atmosphere, he said. It gets blotted out but weve still got light waves refracting around us and sneaking by. You always have some light making it by.
The atmospheric refraction is the same phenomena that makes Mount McKinley appear tall on the horizon from Fairbanks some days even though the mountain, nearly 160 miles away, shouldnt be that visible.
This eclipse will be visible, at least in part, across the Americas and Eastern Asia. However, much of the United States, with the exception of Alaska and portions of the West Coast, will only see a few minutes of the eclipse before the moon sets. Sky gazers in Alaska will get to watch the entire eclipse unfold from start to finish.
Were well positioned for lunar eclipses, Gutoski said of Alaska. Sometimes we have an advantage over the states, at least on the lunar stuff.
That advantage comes with our high latitude, he said, and the fact that often the moon goes all the way around the Arctic sky without dipping behind the horizon.
The weather should cooperate Tuesday morning, Fischer said. There may be some late afternoon or evening showers Monday, but the clouds should be pretty well dissipated by midnight. There might be some ground fog in low-lying areas such as in Creamers Field, he said, but sky gazers who get up on a hill should have an amazing view of the moon.
Lunar eclipses often dont get as much attention as the solar variety when the moon travels directly between the Earth and the sun, momentarily blocking out this planets resident star Gutoski said.
Theyre not as sexy, he said. You dont get as much fireworks because youre not looking at the sun.
But lunar eclipses, unlike solar, dont require any special equipment to view safely. The naked eye will be sufficient, he said, but even a low-powered telescope or binoculars can really liven things up.
You can see a shadow go across some of the big craters and some of the moons mountains, Gutoski said.
Because of the early hour of the eclipse, the Fairbanks Astronomical Unit doesnt have any special programs scheduled for viewing the eclipse, but Gutoski said he knew of several die-hard amateur astronomers planning to take up positions around town.
Fischer said hed brave the morning hours Tuesday to catch the eclipse.
This is an unusually good opportunity for people to see an eclipse, he said. It may be a while before we have another opportunity.
The next time Fairbanksans will get to see a total lunar eclipse like this from start to finish will be Dec. 21, 2010.
