Coming on the evening of Feb. 20 is an astronomical spectacle which should be a rare treat for Texan eyes and amateur astronomers especially: a total lunar eclipse.
Unlike solar eclipses, lunar eclipses are perfectly safe to watch with the naked eye, as well as with binoculars or telescopes, which should help enhance the red coloration the moon will take during the phenomena. The event should be visible across the eastern and southern Continental United States as well as western Europe.
Although eclipses seem to occur rarely, the phenomena are a fairly regular occurrence in cosmic terms. In the last 5,000 years, there have been over 7,700 lunar eclipses, partial and total, which average to around one and a half per year.
It is entirely possible to have no lunar eclipses of any kind in a year or as many as three. The last time there were three lunar eclipses in a year was in 1982, and the next time will be in 2013, but none of them will be total.
The last total lunar eclipse fully visible in Texas was on Oct. 27, 2004, though the view in Dallas was at least partially obscured by cloud cover. It looks as though after nearly four years, Dallas residents may once again suffer the same fate.
The outlook for the evening is cloudy according to weather.com, which means Dallas residents may yet have to wait another few years before getting their next chance, much to the chagrin of stargazers, astronomers and photographers alike. The next total lunar eclipse, which will be visible in Texas, will take place on Dec. 21, 2010.
The beauty of a full moon is that it rises and sets fully opposite the sun, giving it the longest duration of time possible in the night sky, and making all eclipses a striking presence.
An eclipse occurs when the full moon passes through all or part of the Earth’s shadow. Because the Sun is so much larger than the Earth, the sheer size of it means that light from the Sun hits the Earth both head-on and from an angle, creating two shadows for the moon to pass through.
The larger shadow, the penumbra, is the shadow created when the Earth only blocks some of the Sun’s rays, and the smaller shadow, the umbra, is created when the Earth blocks all of the Sun’s rays. A total lunar eclipse can occur only during a full moon and only when it passes completely through both shadows, as it will on Wednesday night.
The eclipse will begin at 7:43 p.m. Central Standard Time and end at 11:09 p.m. The mid-eclipse, the highlight of the event, will occur at 9:26 p.m.
The word eclipse in this case is a misnomer. During most eclipses, the moon is never fully obscured from view. One phenomenon that happens during a total lunar eclipse is seeing the moon appear to turn orange, and in some cases, deep blood-red at full eclipse.
This happens because as the Earth begins to block out sunlight to the moon, some of that light shines through the Earth’s atmosphere. In the atmosphere most of the light in the blue spectrum is filtered out, like a prism, so the red and infrared spectrums make it to the moon’s surface, giving it a deep orange hue unique to the phenomenon.
The brightness and color visible is directly proportional to the amount of dust in the Earth’s atmosphere, such as in 1992 when the eruption of Mount Pinatubo in the Philippines rendered an entire eclipse practically invisible.
Fortunately, there has been no volcanic activity recently, so the show on Wednesday, for those who get to see it, promises to be vivid and clear.
