The year’s first eclipse

Today’s eclipse of the Moon is visible across and around the Pacific Ocean.

See the end note about enlarging illustrations.

These are views of the side of Earth facing the Moon, at the beginning of partial eclipse, mid eclipse, and the end of partial eclipse.  They are views of Earth and Sun as they would be seen by a person on the Moon.

The pictures are arranged in time from right to left because the Man in the Moon would see Earth apparently traveling backward.  Really both are traveling forward around the Sun, but the Moon more rapidly as it passes through its New and Full positions, on the sides nearer to and farther from the Sun.  The broad arrows show Earth’s flight along the ecliptic plane in one minute, and the arrows on the equator show its rotation in one hour.

The reddish glow around Earth is the sunlight coming through the atmosphere over the horizon at the terminator (the boundary between our day and night) and refracted into Earth’s shadow’  This is what causes the coppery colors on the eclipsed Moon, varying from place to place on the Moon and from eclipse to eclipse, because of the varying cloud and pollution at locations around the horizon.

In each picture, countries on the right are about to move out of sight: for them the Moon is setting and the Sun is about to rise at the same time.  Countries on the left have just come into view of the Moon at the end of their day.  Places that appear in all three pictures see the whole course of the eclipse.

Thus, all of the Americas sees some of the eclipse, except for the Arctic archipelago, Newfoundland, eastern Quebec, and the north-eastern tip of Brazil.  The rest of the Americas sees penumbral and partial stages of the eclipse, before the Moon goes down in the west at dawn.  But southwestern Alaska sees total eclipse late in the night, and the Aleutian Islands and Hawaii see it high in the sky.

This is a year with two eclipse seasons, each of two eclipses – the normal and minimum number.  There can be five eclipses, or even six, as last year.

In this picture, Sun, Earth, and Moon are greatly exaggerated in size.  The Moon is shown going through its Full position.  Its orbital plane is shown, darker blue when north of the ecliptic plane, lighter blue below.  The line between those is the lines of nodes.  An eclipse season happen when the Moon is near enough to ascending or descending mode.  The May 26 Full Moon is just before the descending node.  So the Moon passes through the northern half of Earth’s shadow.

The direction in space is toward the constellation Scorpius.  In fact it is the middle of the narrow northern piece of Scorpius, between the wider parts of Libra to the west and Ophiuchus to the east through which the ecliptic runs.  Nu, Beta, Omega, and Delta Scorpii are part of the ragged north-south line of stars forming the scorpion’s menacing front

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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image”, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

Sometimes I make improvements or corrections to a post after publishing  it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.

This weblog maintains its right to be about astronomy or anything under the sun.

 

7 thoughts on “The year’s first eclipse”

  1. Thank you Guy! I miss the annual diagram of the Moon’s orbit around the Earth and the Earth’s orbit around the Sun from the Astronomical Calendar. I would look at it every morning, it helped me stay oriented. I still do my best to visualize where everybody’s at each morning. I’m going to print out the diagram, that will make things much easier!

    I went to bed early yesterday evening and got up around midnight, walked up Bernal Hill to watch the eclipse. I saw the first penumbral and partial phases, all of totality, and most of the second partial phase. Two friends joined me, and there were other lunatics out on the hill. The weather cooperated, mostly clear, with a waxing and waning marine layer, but the fog mostly stayed away from the Moon until late in the second partial phase, when the Moon was about to set anyway.

    It was a beautiful eclipse. I especially enjoyed watching the moonlight fade, shadows disappear, and stars come out as the partial phase progressed. I could not tell when total eclipse began or ended, the Moon never looked fully eclipsed. The northern edge of the Moon stayed bright throughout the total phase, with the brightest part rolling around from lunar northeast (celestial northwest) to lunar northwest (celestial northeast) as the Moon moved through Earth’s shadow. The edge of the Moon opposite the brightest part was much darker and tinged slightly orange.

    Saturn and Jupiter were visible too.

  2. I thought Nu, Beta, Omega, and Delta were the points of the two pincers. But you’re right. They are the scorpion’s head. The claws used to be the stars of the constellation Libra.

    Thank you for the charts and the time you put into the finer details of your posts.

    Your chart of the view from the moon made me wonder if city lights can be seen from the moon. If so, they may be more prominent when a person on the moon is within Earth’s umbra.

  3. Don’t forget the solar eclipse over the Artic on the 10th of June.i live in north east England so will get about 10 percent coverage obviously less as you go south. as London is about 4 degrees south of here perhaps the eclipse will only clip the Sun down there? just sent for some solar film and strangely enough it came from Tel Aviv in Israel.Just thinking of places I’ve been when I’ve seen solar and partial solar eclipses; London, England, Skopje, Macedonia(now North Macedonia,I saw it on Marshall Tito Terg (Square) which is probably called something else now?), Oxford, England and Pietermaritzburg,South Africa.the only place I recall seeing a full lunar eclipse is Liverpool, England.Partial lunar eclipses are very disappointing and hardly worth bothering about.

    1. I love partial lunar eclipses. It’s the only time you can see the edge of the Earth’s shadow, and the only time you can see how fast the Moon is orbiting the Earth. The ancient Greeks (and maybe others?) used partial lunar eclipses to deduce that the Earth is spherical, to correctly calculate the relative sizes of the Earth and Moon, and to make a reasonable guess as to the distance between them. Definitely worth getting up for.

  4. Second paragraph reads in part, “[r]eally both are travelling forward around the Sun, but the Moon more slowly as it passes through its Full position”.
    Should be more “rapidly”.

  5. I’m watching the eclipse at the moment. There are very good views from Sydney on a chilly, crystal clear autumn night.

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