KRISTY GRAY Star-Tribune staff writer | Posted: Wednesday, February 20, 2008 12:00 am
Turn your eyes upward tonight: You'll see the full moon slowly disappear and turn a deep but dim purple before reappearing in the nighttime sky.
If the clouds cooperate, that is.
Tonight, the Earth will pass directly between the sun and the moon, creating the only total lunar eclipse of the year, according to NASA's Eclipse home page, sunearth.gsfc.nasa.gov/eclipse.
It will be the last chance to see a total lunar eclipse until Dec. 21, 2010.
A total lunar eclipse occurs when the moon passes completely behind the earth's shadow. The shadow is actually composed of two cone-shaped parts, one inside the other. The outer shadow is known as the penumbra, the portion of the shadow where the Earth blocks some, but not all of the sun's light. The inner shadow, or the umbra, is the portion where the Earth blocks all of the direct sunlight reaching the moon, thus completely eclipsing the moon's reflected light, according NASA.
In Wyoming, look to the eastern sky at about 6:40 p.m. It will take about an hour and 20 minutes for the moon to pass through the penumbral shadow, into the umbral shadow and into totality - the point at which the Earth completely blocks the sun's light.
The partial eclipse will begin at 6:43 p.m. when the moon's eastern edge slowly moves in the Earth's umbral shadow. Tonight's totality will last just under 50 minutes before the moon passes out of the Earth's shadow from the opposite side.
Totality will begin at about 8 p.m. and end at about 8:50 p.m.
Lunar eclipses can only take place during a full moon. That fact makes these astronomical events especially easy to watch and especially beautiful.
That is, of course, if clouds don't block the view. Pray for clear skies. The forecast calls for partly cloudy skies with a low of 19 degrees.
Check it out:
- What: Public viewing of the lunar eclipse hosted by the Central Wyoming Astronomical Society. The group of amateur astronomers will set up six telescopes - four pointed at the moon, one pointed at Orion's nebula and one pointed at Saturn's rings. Saturn and the bright star Regulus will be visible very near the moon when the sky is darkened by totality.
- When: 6:30 to about 10:30 tonight.
- Where: The front lawn of the Casper Planetarium, 904 N. Poplar St.
- Cost: Free.
- On the net: For more information about the Central Wyoming Astronomical Society, go to http://www.cw-as.com.