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Sun-Earth-Moon relationship: First total lunar eclipse of 2011

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Aira Idris Aira Idris | 13:15 UK time, Tuesday, 14 June 2011

Distance travelled ~ 424'512'000 km: day 165

One of the few significant things Earth and the Moon share is their relationship with the Sun. To an observer on Earth at least - as different portions of both the Earth and Moon's surfaces are illuminated, this signifies the movement of time and the root of our calendar, which is very important.

On 15th/16th June we will observe a unique point in the Sun-Earth-Moon annual relationship - a total lunar eclipse and the first for this year.

total lunar eclipse 2000

Image courtesy of Fred Espenak/NASA

It takes the Moon 27 1/3 days to orbit the Earth (lunar month 29 ½ days), going through the new Moon, first quarter, full Moon, last quarter and back to new Moon. A total lunar eclipse happens when there's a full Moon and the Moon passes through a part of the Earth's shadow, known as the umbra - an area not directly receiving the Sun's rays.

Although there is a full Moon every month, we don't get a total lunar eclipse each month because the Moon's orbit is not in the same plane as the Earth's around the Sun (the ecliptic). From the image below we can see that the Moon's orbit goes over and under the Earth's orbital plane around the Sun.

geometry of a lunar eclipse

Image courtesy Wikimedia commons

The inclination of the Moon's orbit is around 5 degrees to the Earth's orbit, and passes through the ecliptic only twice a month at a pair of points called the ascending and descending nodes. This is where the Nodal Axis is aligned with, or pointing at, the Sun.

The period when the Earth completely blocks the Sun's rays from the Moon is when we experience a total lunar eclipse - known as totality. This moment repeats itself every 6 months.

For this week's eclipse the best placed observers to see it in it's entirety are those in East Africa, central Asia, Middle East and West Australia, lasting a total of 1 hour and 6 minutes. For Europe and South America we will miss the beginning of the show and places like west Australia will miss the end - check specific times for your location. North America completely misses the total lunar eclipse.

Penumbral Eclipse Begins: 17:24:34 UT
Partial Eclipse Begins: 18:22:56 UT
Total Eclipse Begins: 19:22:30 UT
Greatest Eclipse: 20:12:37 UT
Total Eclipse Ends: 21:02:42 UT
Partial Eclipse Ends: 22:02:15 UT
Penumbral Eclipse Ends: 23:00:45 UT

(credit NASA)

What can you expect to see? The shade of the Moon at eclipse is hard to predict because of the Earth's atmosphere. Although the Earth will block out the Sun during totality, the Sun's rays will still penetrate through the Earth, and mixed with the dust and cloud in the atmosphere the total lunar eclipse may take a variation of different shades. Volcanic ash can also affect the shade of the total lunar eclipse - turning it a darker shade of red. Ash from the recent eruption of the Puyehue volcano in Chile may have placed some sulphur dioxide into the stratosphere, according to atmospheric scientist Richard Keen of the University of Colorado.

If you plan on observing or photographing the total lunar eclipse of June 15th/16th and would like to share your comments and images with the 23 Degrees team for a possible story or image gallery do get in touch.

The next long lunar eclipse will be in 2018.


  • Comment number 1.

    I watched the recent Sky at Night and 2 news briefings today (15th June 2011) and I did not see anything to alert me to this event. In India it is being headlined as the darkest the Moon has been in its full-moon phases for 100 years, due to its proximity to the centre line. I may pick up the Metro newspaper in a while, they have a handy science section.

  • Comment number 2.

    Hello Mike
    Tonight's eclipse is very significant and yes that's due to two things. It will be a very long eclipse, just shy of the maximum 1 hour and 7mins (last long total lunar eclipse was in 2000) and because as you mentioned the Sun, Earth and Moon will be in an almost perfect line.

    In response to your comment about the lack of coverage, I believe Sky at Night magazine covered the event in their June issue, and hopefully it will pick up throughout the day

    Either way, if you are planning on observing it, the 23 Degrees team would love to see your photos?


  • Comment number 3.

    I have been doing some research and one of the conclusions I have is that lists of lunar months are included in the Bible which give a good indication of the distant past. Adam didn't really live 900 years. He wasn't real. He is the moon with a story wrapped around him. 900 is the area of a circle representing the orbit. The same with those who follow. The keep on reducing until there is a normalising when all men only go as far as 70. In Revelations, the Beast is 666 which is an orbit of 29.3. We are now at 27.3. The first observations point to 32. Is it therefore possible that the moon is actually slowing down and moving closer to Earth so that its path through the sky looks unchanged? The only way to see the change would be by comparing it to the sun. Tables to calculate eclipses are always having to be modified. Recreating an eclipse based on a historic text never works. Are we sure of our facts? If the moon is slowing then this would explain that? For the moon's orbit to shrink and then go backwards again would require a force which would affect the Earth as well.

    Here is the data. In the Bible they use time as the third dimension

    Time Orbit Time + orbit Radius Diameter Circumference
    0 115 800 915 15.95769122 31.91538243 100.265131
    115 105 807 912 16.02735406 32.05470812 100.7028355
    220 90 815 905 16.1065998 32.21319961 101.2007512
    310 70 840 910 16.35176762 32.70353525 102.7411861
    380 65 830 895 16.25414426 32.50828851 102.1278004
    445 162 800 962 15.95769122 31.91538243 100.265131
    672 187 682 869 14.73388416 29.46776832 92.57572446
    859 182 595 777 13.76206315 27.52412631 86.46959301
    1041 500 450 950 11.96826841 23.93653682 75.19884824

    Many thanks for any ideas


  • Comment number 4.


    If the Moon is Adam, is Eve the eclipse?

  • Comment number 5.

    It's interesting I didn't know that the lack of gravitational force was the reason the moon has no atmosphere. Have you heard (I'm sure you have) of the work of Michael Greene (he's written a lot of books on string theory)? I really like his explanation of gravity.

    Quick question, what do you think the relationship is (if any) of the spiral action of orbits like, tornadoes, hurricanes, whirlpools, the centrifugal actions of the earth and all planets of themselves along with the entire orbital rotations of galaxies etc. Is there an organizational and structuring phenomenon going on with all of these things spinning the way they do? Is it a way of somehow harnessing energy?

    [Unsuitable/Broken URL removed by Moderator]


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