(Credit amp Copyright Martin)
April 13, 2014|By Tamara Dietrich, tdietrich@dailypress.com
Skywatchers will be up in the wee hours Tuesday to view a "blood moon" a total lunar eclipse that also happens to be the first of four consecutive total lunar eclipses set to occur through next year.
The phenomenon is called a "tetrad" of lunar eclipses and, while not unique, does stand out this time in one regard.
According to NASA eclipse expert Fred Espenak, "The most unusual thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA."
Here in Hampton Roads, look toward the southwest horizon beginning around 2 a.m., said Robert Vold, professor of applied sciences at the College of William and Mary in Williamsburg and director of its Thomas Harriot Observatory.
The moon should appear close to the planet Mars, which is also shining especially bright right now as it undergoes what's called "opposition," when it and the sun align on opposite sides of Earth.
Around 3 a.m., NASA says, the lunar eclipse "totality" will occur during a 78-minute interval.
"If it's a clear night, I might just try to go up and take a picture of it," said Vold. "It won't be totally invisible. It'll still be shining faintly in a kind of reddish, ugly-looking light."
That reddish light is what gives a blood moon its name.
A lunar eclipse occurs when the Earth is positioned directly between the sun and the moon. From the moon's vantage point, NASA says, the Earth is rimmed with a fiery light that beams into Earth's shadow and in turn gives the moon an amber glow.
The moon's plane of orbit is a bit tilted, Vold said, which is why a total eclipse doesn't happen every month.
A total lunar eclipse isn't just a pretty sight for skywatchers. Vold said professional astronomers with high-powered telescopes can gather important data about the elemental composition of stars just as they vanish on the edge of the moon.
And tetrads aren't rare except when they are.
This century, for instance, NASA says to expect nine of them. One tetrad already occurred in 2003-2004.
Meanwhile, according to Espenak, in the 300-year interval from 1600 to 1900 there were no tetrads at all.
Vold says he knows of no plans among local amateur or professional astronomers to gather for a glimpse of Tuesday's blood moon.
The matter may be moot: Weather forecasts for the area call for mostly cloudy skies through Monday and rain into Tuesday.
Mike Rusnak, a meteorologist at the National Weather Service in Wakefield, said overcast conditions in Hampton Roads might make it difficult to see.
"(It's) not completely out of the question," he said, "(but there's a) very low chance of it being visible."
The next three total lunar eclipses are calculated to occur on Oct. 8 this year, then on April 4 and Sept. 28 next year.
Dietrich can be reached by phone at 757-247-7892. Reporter Sarah J. Pawlowski contributed.
Source: http://www.dailypress.com/news/science/dp-nws-blood-moons-20140414,0,7218206.story
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