Next week’s total lunar eclipse – a celestial trifecta
At 1:17AM on Tuesday December 21st, the Moon will reach the midpoint of the first total lunar eclipse visible from North America in nearly three years. The last one happened on February 20th, 2008. Unfortunately, the view above my home in Santa Fe was blocked by clouds. Hopefully this time I’ll have better conditions or it will be a long wait until the next total lunar eclipse on April 15th, 2014.
A total lunar eclipse happens when the Moon passes through the shadow of the Earth. This alignment occurs at least twice a year. The Moon is always full during a lunar eclipse because its position is opposite us from the Sun. But, since the angle of the Moon’s orbit is inclined about five degrees from the plane of Earth’s orbit, we don’t get a lunar eclipse every month.
During the penumbral or partial phases of eclipse, we get a chance to see our home planet’s profile as a gentle arc of darkness moving across the face of the Moon. A feature not lost to ancient Greek philosopher Aristotle whose observation of this curved shadow led him to conclude that Earth is a sphere.
As the eclipse reaches its total phase when the umbra or darkest part of the Earth’s shadow falls upon the Moon, we usually see a dusky red hue across the lunar surface. This happens because lower frequency wavelengths of light – the ones we see as orange and red – pass more easily through the blanket of the Earth’s atmosphere.
We see that same light each day painted across the sky at sunrise and sunset. An observer standing on the Moon would see Earth’s silhouette ringed by this ruddy light. Just how deep a red we see depends upon the amount of pollution, dust or cloud cover in the atmosphere. Clouds of ash from volcanic eruptions can enhance umbral shadow color. As the moon darkens, countless stars previously swamped by bright moonlight become visible.
For this eclipse, the Moon will appear very high in the sky, nearly overhead. Higher than any full Moon between now and 2020.
But wait, it gets even better. This lunar eclipse delivers a celestial trifecta. The winter solstice, a full moon and a total lunar eclipse all fall on the same day. A rare combination of events that won’t be repeated until 2094!
So, even if you landed on the naughty list this year, you can still revel in the glow of a heavenly gift unsurpassed by any manufactured holiday trinket.
Check the graphic and the table below for eclipse timings (times shown are MST)
| December 20th | 11:33 PM | partial eclipse begins |
| December 21st | 12:41 AM | total eclipse begins |
| December 21st | 01:17 AM | mid-eclipse |
| December 21st | 01:53 AM | total eclipse ends |
| December 21st | 03:01 AM | partial eclipse ends |
click for a larger version
Nice site Peter……