Moonshadow tomorrow

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A few mornings ago the Moon’s slender C-shape could still be seen before the Sun rose; then it got too slender and too close in the brightening sky, Here is how the east looked to me this morning half an hour before sunrise.


I hurried home to paint this sketch from memory, and I think the sea should be lighter and greener, the upper sky darker and the clouds not so brown (but I didn’t want to paint in gray). The Moon may have been buried in that orange glow, but I wouldn’t have been able to see it even if I’d remembered to try.

Tomorrow, October 23, it will be in front of the Sun. In front of the upper part of the Sun, that is, since this New Moon moment will happen 21 hours after the Moon crosses its “ascending node” – crosses the Sun’s path northward.

The timing is such that Europe will again have moved around into night but most of North America will still be facing the Sun. (The New Moon moment is 22 hours by Universal Time, so 21 (9 PM) by clocks still on British daylight-shifting time, 5 PM in America’s Eastern time zone, 2 PM in the Pacific zone.)

So, if you live in the western states or western Canada, daylight will appreciably dim in the afternoon, and if you look up you will see that it is because the invisible Moon has taken a piece out of the upper edge of the Sun.

If you are farther east, anywhere from the Canadian Arctic islands to the Plains and to Texas and Yucatán, this partial eclipse will happen when the Sun is well down toward the western horizon. Farther east again, from Hudson’s Bay to the Great Lakes to Florida, you’ll be lucky if you see the eclipse just beginning. Yet farther east, in eastern Canada and in New England, the eclipse begins as or after the Sun sets.

Please, if you look at the Sun, look EITHER VERY BRIEFLY OR WITH ONE OF THE TRULY SAFE METHODS. Not, for example, through a piece of exposed film.

The homemade safe method is to let the Sun shine through a pinhole in a sheet of card onto another sheet of card, forming a perfect little image of the Sun’s shape.

Best, however, is to have a piece of Number 14 welder’s glass. This rectangular thing of playing-card size appears entirely black if you look at anything through it other than a blaze of welding sparks or the Sun. If you don’t have this item and can’t acquire it in time, I suggest you acquire it next week anyway. Why? Because you need to have it in 2017, and if you don’t get it soon you may forget.

On 2017 August 21 happens the real spectacle: a total eclipse of the Sun, whose narrow path will cross the U.S., from Oregon in the morning to Kentucky at noon, ending just after noon by traversing South Carolina from Greenville to Charleston. We’ll return for that occasion.


9 thoughts on “Moonshadow tomorrow”

  1. One cool thing to notice during a partial solar eclipse is that nature provides us with natural “pinhole cameras”. For example, when standing beneath a leafy tree, you often see at your feet, between the shadows cast by the leaves, a mishmash of moon-nibbled solar images.

    If no suitable structures are nearby, a similar “pinhole” effect can be created using your own fingers. Spread the fingers of both hands wide, place your two hands together such that the fingers of one hand cover the fingers of the other hand at approximately right angles, and allow the Sun to shine through the grid thus created onto a makeshift screen of some sort. The screen can be a handy wall, a piece of white cardboard, etc. Improve results by experimenting with the sizes and shapes of the several “pinholes”, and with the distance and angle between your hands and the screen. Etc.

    The images are of course not perfect and it may require a bit of imagination to see them. I am reminded by their existence that there are many interesting things, seen and yet-to-be-seen, under the Sun.

  2. Good thing we just had practice finding a good spot for photography of an object low on the western horizon just two weeks ago! We should all be able to go back to the same spot where we saw the lunar eclipse to see this partial solar one. I’m also looking forward, as Anthony Barreiro is, to viewing the eclipsed Sun with AR2192 front and center.

  3. I’m hoping for skies clear enough to see the eclipse here in San Francisco, although the weather forecast calls for partly to mostly cloudy conditions with a chance of much needed rain. I’m planning to take the day off from work, and if the weather cooperates I’ll be in the park on top of Bernal Hill with a couple of solar telescopes.

    By the way, if the Moon is north of the ecliptic and we’re observing from the northern hemisphere, I expect to see the Moon take a bite out of the Sun’s upper (not lower) edge. If so, the huge sunspot AR2192 will also be visible, presenting an excellent opportunity to see that sunspots are not perfectly dark, like the eclipsing Moon, but are merely much less bright than the rest of the Sun’s surface, thus appearing dark by contrast.

    Also, I would never encourage anybody to look at a partially eclipsed Sun with unprotected eyes, no matter how briefly. The risk of eye damage is too great. Get a pair of inexpensive mylar eclipse glasses or a piece of welder’s glass, or make a pinhole camera. You’ll see more detail and you won’t fry your eyeballs.

    1. I meant to say that the Moon has taken a piece out of the “upper” edge of the Sun, of course, and have corrected it now.

      1. Mercury still appears to be retrograde until Saturday, turning our minds and words head over heels.

  4. If we are lucky in western Virginia, we will be able to see a bite taken out of the sun as it sets. The event becomes noticeable about 6 pm EDT with the sun only 6º above the horizon. A interesting photo op?

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