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Featured Stargazing U.S. Solar Eclipse of Aug. 21, 2017

  1. Jun 8, 2017 #101

    1oldman2

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    Thanks for the "Heads up" :wink:
    And NASA is putting on a "Two month to the Eclipse" event.
    https://eclipse2017.nasa.gov/save-date-june-21-2017
     
  2. Jun 8, 2017 #102

    OmCheeto

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    Actually, I just doubled checked, and the eclipse will only be at 45° above the horizon where I plan on being at.
    It looks like it will be at around 63° at maximum.

    ps. I did some spectral testing on the 1st of June, and IMHO, it was a dismal failure.

    2017.06.01.1323.eclipse.spectral.test.png
    The "rainbow" in the upper right hand corner is why I was interested in BillTre's "Very Dark Black" thread.
    My redneck paper towel tube lined with black craft paper and held together with duct tap solar filter device seems to still be leaking light.

    2017.06.01.solar.eclipse.redneck.setup.png

    Which is a good thing, as it gives me time to research this some more, and maybe whittle something out of a tree branch, as the above device tended to fall off if the wind blew, or I moved the camera, or the camera decided to turn off and retract the lens, at which point the wind would blow it across my driveway.

    And my brand new garage sale tripod is much more robust than the one I picked up last year. 1/3 the price, also.

    pps. Here's another image of a solar spectrum:

    The Flash Spectrum of the Sun [APOD]
    Image Credit & Copyright: Constantine Emmanouilidi
    Explanation: In a flash, the visible spectrum of the Sun changed from absorption to emission on November 3rd, during the brief total phase of a solar eclipse. That fleeting moment is captured by telephoto lens and diffraction grating in this well-timed image from clearing skies over Gabon in equatorial Africa. With overwhelming light from the Sun's disk blocked by the Moon, the normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images at each wavelength of light emitted by atoms along the thin arc of the solar chromosphere. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

    (a tad too large for PF)

    But that bolded part just gave me confirmation of what I was already planning on doing. A video. Even though the resolution drops down to 640 x 480, I'm familiar enough with the camera now, that I know it takes a while to focus, and think about other things, before it finally takes a picture. Getting that shot with a dollar store auto focus camera strikes me as nearly impossible.

    hmmmmm...... I do have an old Canon A-1 sitting in the closet, and I do have that spare tripod from last years garage sale. Do they still make that silver based plastic "film" stuff, from the olden days?

    ppps. I also found the one link that APOD mentioned interesting, as I may have just glossed over some of those facts in the past:

    The spectrum of the corona.
    ... The green emission (at a wavelength of 530 nm) was discovered in 1869 and its origin remained a mystery for over 70 years. Because it could not be identified with any element known on the Earth, it was suspected that it might be due to a new element, tentatively dubbed "coronium." (Remember, that helium was first discovered in the solar spectrum and named after the Sun.) Eventually, however, the mysterious green line was shown to be due to thirteen-times-ionized iron, that is, iron atoms with 13 electrons stripped off! This was one of the first indications that the corona is extremely hot; indeed temperatures of several million degrees are required to strip 13 electrons from iron. The search for coronal heating mechanisms continues to this day...

    I've bolded all the thing I find really interesting, or did not know, or had somehow forgotten.
     
  3. Jun 9, 2017 #103

    jim hardy

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    cropped down to

    OMCheeto'sAPOD.jpg
     
  4. Jun 9, 2017 #104

    jim hardy

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    Don't overlook plastic plumbing fittings. All kinds of clever shapes in those bins .

    Rubber band around back of camera ?

    Just how much iron is in the sun? I thought it was still burning hydrogen into helium.
     
  5. Jun 9, 2017 #105

    jim hardy

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    Last edited: Jun 9, 2017
  6. Jun 9, 2017 #106

    Borg

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    That chart makes me wonder how the fusion rates and quantities change as the sun burns through its hydrogen. As you get more helium, its rate of fusion with other elements increases plus, as the hydrogen quantities decrease, the radiant pressure changes which affects the fusion rates as the effective gravitational pressure increases. So many variables... :wideeyed:
     
  7. Jun 9, 2017 #107

    mfb

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    The interior gets a bit hotter and denser, increasing the fusion rate a bit and making the sun a little bit larger and more luminous. Eventually that process will accelerate and the sun becomes a red giant.

    Fusion changes the core composition - the surface composition is a different thing.


    Apart from the helium->hydrogen process, all the elements in the sun come from its initial composition.
     
  8. Jun 9, 2017 #108

    Borg

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    Yes, I should have said a star vs. the sun such that the heavier elements are only created in larger stars and only escape by way of a supernova.
     
  9. Jun 9, 2017 #109

    mfb

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    Well, the Sun will create carbon later in its life, and a little bit of heavier elements.
     
  10. Jun 9, 2017 #110

    OmCheeto

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    Can someone please confirm that the Iron % by mass in the Space.com in Jim's image is incorrect due to a missing zero.

    2017.06.09.Friday.PF.fun.png
    Thanks!

    ps. This was making me want to cry this morning, as I'm really getting tired of my bad maths.......
     
  11. Jun 9, 2017 #111
    My Magic Square of Eclipse Prophesy will predict solar eclipses on or near August 21st. All rows, columns, and diagonals will add up to 10085. There could be a few misses, but it should work pretty good otherwise. The square can be reset to any other eclipse on another year by an additive constant.
    ecl2017.jpg
     
  12. Jun 9, 2017 #112

    mfb

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    Good catch. There are three mistakes.
    Iron should have 0.003 by abundance (a factor 10 less), and 0.14% by mass (a factor 10 more). Sulfur should have 0.0015 by abundance (a factor 10 less).

    @Helios: Where is the prediction? Where are August 23, 2044 or August 24, 2062? 24 August 2101 and 26 August 2147 made it in.
    A few misses? You missed 2 out of 5 in the 21st century.

    22nd century? 26 August 2109, 15 August 2110 (okay, 6 days), 25 August 2128, 15 August 2129 (6 days), 16 August 2156, 25 August 2166, 27 August 2174 (6 days), 26 August 2193, 16 August 2194 - out of these 6-9 only 3 are in.
    We can get eclipses close to August 11 if we adjust add 1 everywhere to have the August 11, 2018 eclipse in the center? Then it would predict an eclipse around August 11, 2037. The last eclipse of 2037 is July 13, 2037. That is about as far away as it can get.

    Where does this square come from?

    Edit: The most common distance is 19 years, which is close to the length of the Saros cycles of 18 years. 9 years as half a Saros appears as well. 46 is the only other difference. 46=18+9+19.
    Starting from 11 August 2018: 9 years later we have August 2, 2027. 19 more for 2046? Indeed: August 2, 2046. +19? August 2, 2065 - spot on. +46? 4 August 2111. +19? 4 August 2130. +46? 4 August 2176
    I can't directly link it to Saros cycles and it misses various eclipses, but it looks like a pattern.
     
    Last edited: Jun 9, 2017
  13. Jun 9, 2017 #113

    jim hardy

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    Well ! So much for space dot com as a reliable source.
     
  14. Jun 9, 2017 #114
    @mfb This square should be good! So August 21, 2017 isn't the best for the center. I'll tweak it and put 1998 in the center. That's subtracting 19 years from every date. This changes the sum to 9990. All these are solar eclipses, with only two partials. It doesn't catch all eclipses, just the close and reliable ones. These I think are Y = 19, 65, 84, 130, 149, 168, 177, 223, 242, 261, 307, 326. and I made the square from these.
    ecl2017a.jpg
     
  15. Jun 9, 2017 #115

    OmCheeto

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    It looks as though they misabsconded the table from Hyperphysics.
    Which they claim to have absconded with from a text book: Fraknoi, Morrison & Wolff Table 14.2, Published 2000

    Trying to find a free copy, I accidentally downloaded a 1200 page, 178 megabyte different text by the same authors: Astronomy, published in 2016.
    They have a similar table with all the same elements, though the numbers have been revised a bit.
    page 526(text book) or 536(pdf)
    Table 15.2
    Code (Text):
    Elem      % by #    % by mass
    H         92.0        73.4
    He         7.8        25.0
    C          0.02       0.20
    N          0.008      0.09
    O          0.06       0.80
    Ne         0.01       0.16
    Mg         0.003      0.06
    Si         0.004      0.09
    S          0.002      0.05
    Fe         0.003      0.14
    Trying to find it, I ran across some really fascinating things:

    Galileo didn't invent the telescope. He was just the first person to use it for astronomy.​

    And just below table 15.2, they mention the following:

    The fact that our Sun and the stars all have similar compositions and are made up of mostly hydrogen and helium was first shown in a brilliant thesis in 1925 by Cecilia Payne-Gaposchkin, the first woman to get a PhD in astronomy in the United States (Figure 15.3). However, the idea that the simplest light gases—hydrogen and helium—were the most abundant elements in stars was so unexpected and so shocking that she assumed her analysis of the data must be wrong. At the time, she wrote, “The enormous abundance derived for these elements in the stellar atmosphere is almost certainly not real.” Even scientists sometimes find it hard to accept new ideas that do not agree with what everyone “knows” to be right.

    Good idea! I actually found one that fit. But the camera was not designed for the addition of auxiliary lenses, so it ended up not working. But I did devise something that will work. I'm almost ready!

    All I need now, is a cardboard box.

    1963.Francis.Miller.lifeeclipseimage.jpg
    1963. Interesting solution when you don't have solar filter material. Actually, I think this is a brilliant idea, for people who can't make it to totality.
     
  16. Jun 10, 2017 #116
    What do you mean ...The points of Greatest Eclipse...will be at the opposite sides of Kentucky. The closest place to me would be in Idaho since I live near Salt lake. So would I be driving up there just to view an almost full eclipse or what?
     
  17. Jun 10, 2017 #117

    mfb

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    Huh?
    Everyone in the band will see a total eclipse. In the center it is longer than close to the edges. At Shelley you have a very short phase of totality, at Idaho Falls it is longer already, and between Rigby and Rexburg you have the longest totality.

    The duration of the eclipse in the center of the band varies a bit as well along the band, but that is a smaller effect.
     
  18. Jun 10, 2017 #118

    OmCheeto

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    per NASA's GLOSSARY OF SOLAR ECLIPSE TERMS;
    "greatest eclipse - For solar eclipses, Greatest Eclipse (GE) is defined as the instant when the axis of the Moon's shadow cone passes closest to Earth's center."​

    Don't feel bad. I had to look it up. As far as I'm concerned, it's an "eclipse nerd" term.

    I don't think it will make much of a difference where you see it from, as long as you're at or very near the blue centerline.
    2017.06.10.eclipse.idaho.utah.map.png
    As, the closer to the blue line you are, the longer totality lasts.

    On the blue line near Idaho Falls, totality lasts 2 minutes and 18 seconds.
    On the red lines, totality last about 1 second.

    Driving all the way to Kentucky to be at the "Greatest eclipse" point, will add about 20 seconds to totalities duration.

    Hardly worth the petrol, IMHO.
     
  19. Jun 10, 2017 #119

    OmCheeto

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  20. Jun 10, 2017 #120

    tony873004

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    Being near the edge has the advantage of longer diamond ring and Bailey's Beads and perhaps prominences. But it comes at the expense of totality duration and darkness of sky. Areas just a mile away from you are in your direct line of sight and experiencing direct sunlight.

    Being far from the "Greatest Eclipse" has the advantage of giving you a longer shadow along the track of the eclipse, perhaps giving you a darker sky at mid-eclipse. You also don't have to strain your neck as much as the eclipse is lower in the sky. These advantages come at the expense of totality duration.

    I got a campsite in Madres at their Oregon Solarfest. It's a 20 x 20 foot plot for my car and my tent. They've planned a large 3-day party complete with classic rock cover bands. We will get 2:03 of totality beginning at 10:19 am, and the Sun will be a comfortable 42 degrees above the horizon.
     
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