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

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    Aira Idris Aira Idris | 13:15 PM, 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.

    23 Degrees photo of the day: Partial eclipse of midnight Sun

    Aira Idris Aira Idris | 16:45 PM, Thursday, 2 June 2011

    d ~ 393'638'400 km: day 153 of Earth's orbit

    Partial Solar Eclipse 2011

    Image captured last night by Oliver Lemke in Sweden.


    An eclipse that occurs at midnight means that we are observing it across the North Pole and the top of the World. The next eclipse of 2011 will be the total lunar eclipse on June 15th, the first total eclipse of the year.

    Tonight brings a rare eclipse of the Midnight Sun

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    Aira Idris Aira Idris | 17:20 PM, Wednesday, 1 June 2011

    d ~ 391'065'600 km: day 152 of Earth's orbit

    Tonight brings a rare sighting for those lucky enough to live in the arctic - a partial eclipse of the midnight Sun. The partial eclipse we experienced on January 4th 2011 saw the moon pass between the Sun and the Earth, partially covering the Sun's view. Tonights partial eclipse however is special because it will be of the midnight Sun. As strange as it sounds there will be a partial eclipse of the Sun at night.

    The Midnight Sun starts in March over the north pole and has its southern most extent on June 21st at the edge of the arctic circle. When either hemisphere is tilted directly towards the sun, the most polar regions are illuminated 24 hours a day, and viewed from Earth the sun is in the sky all day and all night.

    For us in the UK we'll not see this eclipse, but sky watchers in places like northern Norway, Sweden, Finland, Siberia, northern China, remote parts of Alaska and Canada, and Iceland are in for a treat. The eclipse begins at sunrise in Siberia and northern China where the penumbral shadow first touches Earth at 19:25:18 UT. Two hours later, greatest eclipse occurs at 21:16:11 UT according to Fred Espenak of the NASA Goddard Space Flight Center.

    "At this time of year the Sun doesn't set in Arctic parts of the world, so a solar eclipse is theoretically possible at all hours of the day" says Fred Espenak. He goes on to add that "when the clock strikes local midnight in northern Norway at the end of June 1st, about half of the lingering sun will be covered by the Moon."

    map of the June 1st eclipse

    Image © NASA/GSFC (full image here)

    If you happen to spot this then add it to our photography pool. For information on the times that the partial eclipse of the midnight Sun will occur take a look at NASA's timetable.

    And for those who don't want to miss out on this occasion -
    Knut Joergen Roed Oedegaard, an astrophysicist at the Norwegian Centre for Science Education in Oslo will attempt to bring this to us via online automatic photo updates (as part of a project which focusses on the spectacular celestial events 2010-2015).

    If the sun was switched off... well partially

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    Helen Czerski Helen Czerski | 18:26 PM, Tuesday, 4 January 2011

    d ~ 10'291'200 km: day 4

    The Moon always casts a complete shadow somewhere, a constantly moving cone of darkness that points away from the Sun and out into the universe. Most of the time there isn't anything inside the shadow that would notice the darkness, but every so often the Earth passes through this dark region (known as the umbra) and we on Earth get a peek into the mechanics of the solar system. By celestial coincidence, during a total eclipse the Earth is more or less at the point of the cone, so the sun is almost perfectly blocked for a brief period of time while the Sun, Earth and Moon are all aligned. Total solar eclipses like this are relatively rare, but many of us will get to experience a partial eclipse during our lifetimes.

    Here's a great picture of this morning's partial eclipse by a UK photographer:

    Partial Solar Eclipse

    Neil Parley UK / Flickr

    If you wish to share your photography and video of weather phenomena, please email us. Let us know what's happening in your part of the world.

    In European cities like London and Paris, the eclipse was already underway as the Sun rose, and the Moon covered up almost 70% of our star by 0812 GMT in the British capital, and 65% of the solar disc by 0809 GMT in the French capital. The moon's complete shadow just missed the Earth but the outer partial shadow (the penumbra) passed over us.

    Here's an illustration of the conical shadow the moon casts:

    Corono

    Eclipses are not only amazing things to experience, but they've also been very useful for science. When the sun itself is covered during a total eclipse, the corona (the sun's atmosphere) gets its moment of glory. Helium, the second most abundant element in the universe, was discovered in the corona during a solar eclipse in 1868. It had been there in plain sight all along, but the signal from it was overwhelmed by the intense power of the sun's light. Now, rather than waiting for eclipses to occur to study the corona, scientists make artificial eclipses in front of their cameras. For example, NASA's SOHO coronagraph took these spectacular images of the Sun's atmosphere in December 2010.

    Lastly, an eclipse is a powerful reminder of just how important the light from the Sun is for our planet - we get a glimpse of what it would be like if the Sun was switched off. It's the major source of energy for the Earth, fueling plants, animals, the circulation of vast amounts of water around the oceans, and most importantly for this blog it's where energy for the weather comes from. We see hurricanes, blizzards, gales and tornadoes as powerful events, but they're all just concentrating a tiny fraction of the energy that we get from the sun every day into a relatively small area. With all that in mind, here's to the next partial eclipse June 1st 2011!

    Helen Czerski is co-presenter of 23 Degrees

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