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Friday, July 27, 2018

longest lunar eclipse ~ Blood Moon today - 2018


The longest total lunar eclipse of the century will be today. While the full eclipse will be over 6 hours, the total lunar eclipse 2018 - when the moon will be in the middle of Earth's shadow - will last for 1 hour and 43 minutes. The total lunar eclipse today will be the longest such eclipse for the next century, until June 9 2123. Moreover, today's eclipse is also the Blood Moon  ~ remember we enjoyed seeing this on 31st Jan 2018. 

A lunar eclipse is a celestial event which happens when Earth lines up directly between the sun and the moon. When this happens, Earth blocks the light from the sun to the moon. Earth's shadow then falls on the moon. During a lunar eclipse, we can see Earth’s shadow on the moon.    An eclipse occurs any time a planet or moon passes between another planet, moon or the sun. Depending on their orbits, they can be total or partial. They can last for several hours, but it is rare for a period of total eclipse to last longer than 100 minutes.  At least two lunar eclipses happen every year.

A total lunar eclipse happens when the whole moon enters Earth's shadow. Some sunlight still reaches the moon, but first it goes through Earth's atmosphere. The atmosphere filters out most of the sun’s blue light, so the moon looks red.

On Friday, July 27th, a "blood moon" lunar eclipse will happen. The full moon passes through the shadow of Earth. What is special about this particular eclipse is that it will change the color of the moon to a reddish color. Obviously that is where the term "blood moon" comes from but, this one will happen for about 103 minutes.  At the same time that the longest "blood moon" in history occurs, Mars will be only 35.9 million miles from Earth. According to experts, this is the closest that the "red planet" has been to Earth in 15 years.

You all would have heard the phrase :  ‘Once in a blue moon’ ~ informally it would mean ‘very rarely’.  Synonyms:  hardly ever, almost never, scarcely ever, rarely, very seldom.  Interestingly, the colour of moon is never blue. A blue moon is an additional full moon that appears in a subdivision of a year: either the third of fourth full moon in a season, or the second full moon in a calendar month. The phrase has nothing to do with the actual color of the moon, although a literal "blue moon" (the moon appearing with a tinge of blue) may occur in certain atmospheric conditions.

One lunation (an average lunar cycle) is 29.53 days. There are about 365.24 days in a tropical year. Therefore, about 12.37 lunations (365.24 days divided by 29.53 days) occur in a tropical year.   Each calendar year contains roughly 11 days more than the number of days in 12 lunar cycles. The extra days accumulate, so every two or three years (seven times in the 19-year Metonic cycle), there is an extra full moon. The extra full moon necessarily falls in one of the four seasons, giving that season four full moons instead of the usual three, and, hence, a blue moon.

Now getting back to “super blue blood moon”  ~ it will be at its attractive best to those watching !  as the light from the sun passes through the Earth's atmosphere, it will cast a crimson sheen over the moon. Dr Mark Birkinshaw, a professor of Cosmology and Astrophysics at the University of Bristol, told MailOnline that the phenomenon is the same reason the sun appears a dark shade of red when it sits low in the sky. 'The light that passes through the Earth's atmosphere hits the Moon and then gets reflected back to us, and it will be red,' he said. 'Technically, the red light is less scattered by the atmosphere than the blue, so more of it gets through.

'From the Moon, the Earth would appear to totally-eclipse the Sun, and would show as a dark shadow with a bright red ring around it.' The total eclipse begins at 7:30 pm UTC (8:30 BST), and ends at 9:13 pm UTC (10:13 BST). The peak of the eclipse will occur at 8:22 pm UTC (9:21 BST). Only those in the Eastern Hemisphere will be able to view the upcoming event, with people in Europe, Africa and Asia getting the best seats for the lunar show. Skygazers in South America will be able to see part of the final stages of the eclipse just after sunset tonight.  In contrast, New Zealanders will be able to watch the start of the eclipse before sunrise tomorrow morning.

The lunar event will not be visible at all in the United States, as the moon will be invisible below the horizon throughout the duration of the eclipse. By the time it rises across the states, the eclipse will have concluded. Parts of central Asia, the Middle East and Eastern Africa will see the lunar eclipse in its entirety. The UK falls slightly outside of the ideal viewing range, meaning people will see the total eclipse for only 84 of the 103 total minutes. This is due to the moon being below the horizon in Britain when the eclipse begins.

To get the best view of the eclipse, make sure you are in an area with low-light pollution. For example, high vantage points in a built-up area, or ideally, a trip to the countryside should provide the best view. Those who want to photograph the lunar transit will be able to do so with a bit of patience, a telescope and the right app.

Happy moon watching !  The first part of lunar eclipse is expected to start at around 11:44 PM IST on July 27. The Moon will turn red only at the highest point of the total lunar eclipse, which starts around 1 AM on the night of July 28. The phenomenon should last till 2:43 AM IST on July 28.  Those planning to watch this celestial event should note that unlike solar eclipse, one does not need to cover their eyes with protective filters to view the Blood Moon.

With regards – S. Sampathkumar
27th July 2018.


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