BY admin | December 9, 2011
Lunar eclipse December 2011 is round the corner. This Saturday people can get to see a rare morning sight of watching both the sun and the moon together in an eclipse. In Alaska, Hawaii, northwestern Canada, Australia, New Zealand and central and eastern Asia ringside view of the second total lunar eclipse of the year can be had.
The eastern zones of the United States and Canada will see either only the initial penumbral stages before moonset or miss all of it. The central areas of the continent will see the moon setting as it becomes progressively immersed in the Earth’s umbral shadow. The lucky ones in the Rocky Mountain region and the Prairie Provinces will be able to view the full eclipse of the moon.
The moon will totally come under the southern part of the Earth’s shadow at 6:06 a.m. PT and emerge after 51 minutes.
The term given to this unusual sight is “selenelion” (or “selenehelion”). This phenomenon will be visible in most of the United States.
Selenelion is more a quirk of the vision than an actual happening. If we recall our science lessons, we know that refraction bends the light rays when light passes through two media of different densities. Atmospheric refraction causes astronomical objects to appear higher in the sky than they are in reality. So when the sun has actually set, we get to see the sun setting through refraction in the atmosphere. Selenelion occurs because refracted light makes the sun visible though it is nowhere near the eclipsed moon.
This Saturday for roughly one to six minutes, refraction will make the moon appear to be setting to people in the US while the sun is rising on the other horizon.
To the east of the Appalachian Range, this will not be visible because despite the moon being above the horizon when it begins to enter the Earth’s shadow at 6:33 a.m. EST, it will first be met by the penumbral shadow, thus hiding the moon before it can be spied. This will make the moon look very normal in regions like Boston, New York or Miami.
Those in the Upper Midwest, the Nation’s Heartland, down into the central parts of Oklahoma and Texas will see the umbral shadow creeping almost straight down across the moon’s face from its upper limb.
So if you are determined to view this phenomenon, keep watch from an elevated location as you would need both the horizons to be clear of tall constructions or obstructers of vision.
For those in India the second lunar eclipse will be visible throughout Orissa at 5 pm. At 6pm the moon will enter the umbra and the shadowed moon will be clearly visible. It will stay in the umbra till 7.30 pm.
Suvendu Patnaik, the deputy director of Pathani Samanta Planetarium, said, “The shadow will completely cover the moon at 7.36 pm when the brightness of moon will be reduced to less than 40 per cent of its original brightness. It will start leaving the umbra around 8.27 pm and completely exit it at around 9.47 pm.”
This will be the second total lunar eclipse this year. The first was on June 15. Lunar eclipse is a regular phenomenon and occurs at least once every year and may go up to four times a year. A total of seven eclipses can be seen in a year.
Unlike the solar eclipse, a lunar eclipse can be watched with the naked eyes and it is also perfectly safe to venture out in the light of the eclipsed moon! This will also be the second for this year.