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

  1. Apr 2, 2017 #81

    mfb

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    Not this sh... again!

    Yeah, expect traffic jams everywhere.
     
  2. Apr 10, 2017 #82

    1oldman2

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  3. Apr 11, 2017 #83

    tony873004

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    In a few days from now (~April 17-20), the azimuth of sunrise will be the same as on eclipse day, August 21.
    If you happen to live in the zone to totality, this may serve as a good preview of the Sun's position and motion on eclipse day.
     
  4. Apr 11, 2017 #84
    Getting closer every day! ... Looking forward too! ...
     
  5. Apr 16, 2017 #85

    tony873004

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    Here is an updated simulation I made of the eclipse from different cities.
    http://orbitsimulator.com/gravitySim...17Eclipse.html

    The lighting conditions are simply my guess based on partial, annular and total eclipses I have seen. I've never seen the corona as both totals I attended were rained out.
     
  6. May 18, 2017 #86
    I believe I am organizing an eclipse event in Makanda Illinois, for members of this forum, and friends.

    Actually, the location is tentative....

    I wasn't actually intending to organize an event, but hey!, I'm game, if there is interest.

    I have started another thread for this purpose, which can be found here.

    Feel free to chime in.
     
  7. May 18, 2017 #87

    OmCheeto

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    Is that star that shows up in your GIF one of the stars from Leo? Perhaps Regulus?

    I was trying to get an idea of what the sky would look like during the eclipse, so I snooped around in "NASA's Eyes.app", and found a "telescope mode".

    Here's an image where I photoshopped your eclipse image over their star and planet map:

    2017.eclipse.stars.and.planets.png
     
  8. May 18, 2017 #88

    tony873004

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    Yes, the star near the Sun is Regulus.
     
  9. May 19, 2017 #89

    OmCheeto

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    Another question, one of many, is [1]how dark is the sky during totality?
    Is it like midnight? Or more like twilight?

    I just skimmed this thread(and the new satellite thread) and found that of the 21 people responding so far, 6 have been on location for totality, and only two have witnessed it. (stinkin' clouds!)

    My concern with how dark it is stems from something mfb mentioned a while back, as to how long it takes our eyes to adjust to darkness.

    One site I visited says it takes between 10 and 30 minutes for our eyes to become adjusted, depending on how sensitive you want your eyes to be. Since totality only lasts ≈2 minutes, I'm afraid I'll miss the full "hallucinatory" experience, that I experienced when I stuck my head in my oven. (Science!)

    So....

    [2] Should I skip the dollar store eclipse glasses and go for the $20 wrap around models?
    [3] Should I duct tape mylar around my head, until totality?

    ps. My first question also appears to be the topic of a "citizen science" experiment: Activity Guide for How Dark Does the Sky Get During a Solar Eclipse?

    This took me back to where I once discovered that my solar panel's no load voltage is proportional to incident sunlight. [ref] (My wording was a bit off in that post. My apologies.)

    [4] Anyone know where to buy a voltage logger for <$100?

    pps. I have several other questions.
    [5] @tony873004 , is the brightness in your gif just a guesstimation, or is there science behind that? Some of my friends are like; "Whateva.... I'm stayin' home. It'll be 98% covered from my front porch. What's the deal with totality?"

    [6] Where the hell will the Milky Way be? To my knowledge, I've never seen the Milky way. I know the center is in Sagittarius, wherever the hell that constellation is.
    [7] Where is Sagittarius?
    [8] Why is everyone posting; "Google is your friend"?

    ppps. Just as an FYI, I can recognize about 5 constellations: Big & Little Dipper, Cassiopeia, Orion, and Taurus. Everything else, is just a bunch of stars.

    pppps. [9] I wonder how many famous astronomers are from Oregon? Hard to get into a subject when the subject of your study is never visible. (Stinkin' Clouds!)
     
  10. May 19, 2017 #90

    mfb

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    Your eyes keep adjusting to the darkness for a long time, but 2 minutes is more than enough to see the corona.

    It won't get as dark as a moonless night as you are not too far away from regions that do get sunlight, and parts of that light gets scattered. In addition, various man-made light sources will be around.

    98% totality is just a very dark day. 99.9% is a very dark day. The magic happens in the last 0.1%.

    Easier to see during the night. But you'll have to get away from big cities to see it nicely.
     
  11. May 19, 2017 #91

    tony873004

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    I was in Hawaii in 1991, and Shanghai in 2009. Both times it rained during totality. In Hawaii, there were patches of clear sky, but just not where the Sun was. I don't remember seeing any stars or planets. The sky was not pitch black. It was like the same brightness as 25 minutes after sunset. If I had to walk back to my car during totality, I would not have needed a flashlight. It's possible that all the clouds in the vicinity that were not experiencing totality let a lot of light bleed in.

    In Shanghai, the sky was completely clouded over. It got dark like midnight, but the clouds may have had a lot to do with that. In both cases, I was near centerline, and the eclipse path was very wide, producing about 6 minutes of totality.

    My guess is that for the darkest eclipse, you want to be in an area that is cloud-free for a few hundred kilometers, a wide eclipse path, and close to the centerline.

    The August eclipse will not have a wide path. Even at mid-eclipse on the centerline, you will be only 30 miles away from areas not experiencing totality. Any clouds in those areas will be visible to you and reflecting direct sunlight.

    In 2012 I was near Redding, CA for an annular eclipse. The sky was cloud-free. The Moon was rather small compared to the Sun. At the height of annularity, the sky darkened to about the level of perhaps 1 minute before sunset. I had no trouble spotting Venus. I wasn't even looking for it. It just stood out.

    I've read that it takes up to 30 minutes for your eyes to fully dark-adapt. A few years ago, I was a volunteer at my University's planetarium, and experimented with this. I found about 10 minutes was all it took. Maybe they got a little more sensitive over the next 20 minutes, but I didn't notice it. I also noticed that it takes a few minutes for your eyes to un-adapt. For example, with dark-adapted eyes, I stepped out into the hall for a minute. The late-afternoon sun made the hall very bright. But when I returned to the darkened planetarium, my eyes were still dark adapted.

    For August's eclipse, I'll probably wear dark sunglasses (maybe even 2 pairs!) during the partial phase, and have a handheld solar filter. As totality approaches, I'll try to get as dark-adapted as possible. It's tempting to look up at the partial phases. There's the Moon creeping across the Sun. How cool is that! But remember, after totality, it will repeat the partial phases for you. In the 2012 Annular eclipse, everyone was watching the partial phases leading up to annularity, then when annularity ended, they all got in their cars and left. Of the 100+ people at my observing location, there were only a handful of us who stayed to watch the waning partial phases.

    I'm not going to participate in the activity of trying to spot constellations. Totality lasts only 2 minutes. This is the only opportunity I have to see the corona. I'll probably use unfiltered binoculars for a better view. I may take a quick glance just to gauge the darkness of the sky, but if I want to look at constellations, I can do that any night!

    I may set up a 360 degree video camera and just let it run. I don't want to be playing with camera equipment during totality. No matter how nice my photos may turn out, lots of people with better equipment are going to get much better pictures, and they'll be posted all over the internet the next day.

    The brightness in my simulation is just a guess based on having seen 3 annular eclipses, many partial eclipses, and 2 total (but raining) eclipses. I was aiming for what a user may perceive. For example, when the Moon is half covering the Sun, I imagine a light meter would tell me that my surroundings were half as bright. But the human eye doesn't see that. Your eyes sense brightness approximately logarithmically and your pupils dilate making it hard to tell the difference. Until the Sun is about 90% covered, an unsuspecting person won't notice anything unusual. So in my simulation, there's not much difference in the sky brightness with the Sun half covered. In my simulation, even after totality begins, the sky continues to darken until mid-eclipse. I'm guessing that deeper in the umbra is darker, as I am farther away from areas that are outside totality.
     
  12. May 19, 2017 #92

    Janus

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    totality.jpg
    Almost total compared to total. (images taken from screen shots of Worldwide Telescope)
    At the time of eclipse, about 48 degrees to the South, rising upwards towards the South. It takes a clear night well away from light pollution to see it well.
    Below the horizon during the eclipe
    There's a really neat app for your smart phone that can help with that. Just point your phone at the region of the sky that you are interested in and it will show you a labeled map of that part of the sky. (it will even include planets). It is called SkyMap.
     
  13. May 20, 2017 #93

    OmCheeto

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    This is why I love PF.
    Ask for a gram of information, and get a kilogram.

    Well then, it's a good thing I'll be on station for at least 3 days.
    A Google Earth kmz supplied by some very kind people in Germany has yielded me this map:

    2017.05.19.light.pollution.in.OmVille.per.krauts.png
    Red dots, yellow squiggly line, and green ellipse are all actually in the all black zone.




    I still don't have a smart phone.
    But I googled the bejeezitz out of this, and came up with:

    2017.08.21.940.pm.pdt.galactic.center.png
    The yellow bullseye looking thing is the galactic center. I mac-doodle-painted in the "galactic plane"ish stuff.
    I've seen hundreds of images, but am curious what it looks like in real life.

    Bazinga! According to what everyone has posted so far, you've been to the most eclipses(5), and I must say, have had the best suggestions so far.
    I would have never thought to have looked at the partial AFTER the eclipse.

    I was out yesterday, following your instructions from your April 11, 2017 post;

    "In a few days from now (~April 17-20), the azimuth of sunrise will be the same as on eclipse day, August 21.
    If you happen to live in the zone to totality, this may serve as a good preview of the Sun's position and motion on eclipse day"

    and noted that the sun is so high in the sky, that my camera movement is encumbered by the geometry of my tripod.

    And your April 14, 2016 post;
    "With the Sun taking up 50% of the picture, you will be losing the outer edges of the corona. ... Since the Moon has the same angular size as the Sun, take a picture of the Moon with your 300mm lens."

    Apparently, 36x zoom is too much. My image from yesterday:

    2017.05.19.moon.36.zoom.png





    The experiment doesn't even make sense to me. How the hell do you calibrate millions of eyes? That's why I'm taking my solar panel, and collecting voltage data.
    I know @nsaspook has some fancy stuff that does that automatically. Perhaps I can talk him into doing the experiment.

    ps. Ehr mehr gerd. I am so not ready for this. But much readier than I was before. :thumbup:
    Thanks everyone!
     
  14. May 20, 2017 #94

    tony873004

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    Look at the pictures on Miloslav Druckmüller's site.
    http://www.zam.fme.vutbr.cz/~druck/Eclipse/Ecl2016i/0-info.htm
    This will give you a very good idea as to how to frame your image. His images are created from bracketed images, so you get a dynamic range closer to what the human eye sees.

    I just found the video file from my Shanghai trip, and converted it into a Youtube. This was taken by Lancelot Kao, the chairman of the Astronomy Department at City College of San Francisco. I was lucky enough to have met up with him and others in the CCSF Astronomy Department while I was in Shanghai. You can see me a few times in this video. I'm one of the only people NOT holding an umbrella. It was 90 degrees F (~30 C). Being wet felt good, and umbrellas blocked the view.

    This video begins about 2.5 minutes before totality begins.
     
    Last edited: May 20, 2017
  15. May 20, 2017 #95

    Janus

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    The best view of the Milky Way I ever saw came quite by accident. A friend and I were driving up the Oregon coast late one winter night, and he had to pull off at some lonely point of US 101 to do some quick car maintenance. I got out to stretch my legs, looked up, and it was just blazing across the sky.
     
  16. May 24, 2017 #96

    OmCheeto

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    I just found this 360° video. It looks exactly as you've described it.



    Published on Apr 30, 2016
    Experience the Total Solar Eclipse that took place across Indonesia on the March 9, 2016.
    We travelled to see it first hand and it was incredible.

    Listen to the cheer of the crowd and then the breath of silence it brings. It takes people's breathe away.

    Words cannot describe the feeling of a total eclipse. It's as if someone pulled a curtain in front of the sun during the day. Everyone should make it a mission to witness a total eclipse.

    Totality began at 8:37:47 am and ended at 8:39:52 am

    I also found an informational video.



    Probably good for people that don't know anything about eclipses.
    I of course watched it from start to finish.

    2 interesting facts mentioned:

    6:50 "Even if 99% of the solar disc is blocked, the remaining 1% is still 4,000 times brighter than a full moon."
    9:40 "Thin, wavy lines of shadows known as shadow bands will appear on the ground, and scientists to this day, do not yet fully understand how they are created."

    Shadow bands? What sorcery is this?

    What are 'shadow bands'? [NASA]
    These are among the most ephemeral phenomena that observers see during the few minutes before a total solar eclipse. They appear as a multitude of faint bands that can be seen by placing a white sheet of paper several feet square on the ground.They look like ripples of sunshine at the bottom of a pool, and their visibility varies from eclipse to eclipse. 19th century observers interpreted them as interference fringes caused by some kind of diffraction phenomenon. The Sun, however, is hardly a 'point source' and the patterns are more random than you might expect from diffraction effects.

    The simplist explanation is that they arise from atmospheric turbulence. When light rays pass through eddies in the atmosphere, they get refracted. Unresolved distant sources simply 'twinkle', but for nearby large objects, the incoming light can get split into interfering bundles that recombine on the ground to give mottled patterns of light and dark bands, or portions of bands. Near totality, the image of the sun is only a thin crescent a few arc seconds wide, which is about the same size as the atmospheric eddies as seen from the ground. Bands are produced because the sun's image is longer in one direction than another. The bands move, not at the rate you would expect for the eclipse but at a speed determined by the motion of the atmospheric eddies.

    Thanks, NASA!

    hmmmm.... I didn't realize they were so into this. https://eclipse2017.nasa.gov/

    And how cool is this? Citizen Science!
    Too many projects to list.
    I'll have to find one that I can contribute to.

    This one looks like something I was planning on doing:

    GLOBE at night (NOAO) (link is external) – This is an international citizen-science campaign to raise public awareness of the impact of light pollution by inviting citizen-scientists to measure and submit their night sky brightness observations. In 2015, citizen scientists from around the world contributed 8,337 data points. Whether you use a smartphone, tablet or computer, you can submit your data in real time with the GLOBE at Night web app - now available in 28 languages!

    I may have to finally invest in a smartphone........
    Emphasis on "may"......:oldgrumpy:

    --------------

    I also finally ordered some new equipment.

    RAINBOW SYMPHONY STORE
    Thank you Om!
    $27.67
    Solar Viewing Film - Our Black Polymer Solar Filter Film provides a pleasing natural light orange image of the sun.
    2 mil Optical Grade polymer for use on Telescopes, Finder Scopes, Binoculars and Cameras.
    12" x 12" Sheets - Meets the Standard for ISO 12312-2:2015

    https://www.iso.org/standard/59289.html
    ISO 12312-2:2015 applies to all afocal (plano power) products intended for direct observation of the sun, such as solar eclipse viewing.​

    I decided that with a 12x12" sheet, I could make my own glasses, camera lens and binocular covers. And maybe have some left over, in case I ever buy a telescope, and want to look at sunspots, or whatever.
     
  17. May 25, 2017 #97

    tony873004

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    I saw that video too. I've got a Samsung VR headgear for my Galaxy phone. That video looks awesome when it surrounds you. I may decide to drop $250 on a 360 camera so I can make one too. That's the only type of photography I want to do: something where I can turn on a camera a few minutes before totality begins, and turn it off a few minutes after. I don't want to be adjusting a tripod minute-by-minute and messing with exposure time during totality. Hopefully I can capture the approaching and receeding shadow.

    In the Indonesia 360 video, I think it got darker than that. The camera's auto-iris probably kicked in taking advantage of the camera's low-light capability and making the scene appear brighter than a human eye would perceive. If I try that, I'll have to find a way to turn that off.
    I got 2 of these a few months ago. I already made some binocular filters. On a 3-d printer, I recreated the lens caps and put holes in them to accept the film.
    I'm going to use the rest to make a bunch of hand-held cardstock filters.
    I once lived in a house where you could see these every day. A few minutes after sunrise, the sun was still behind a hill about 1 mile away. When it finally peeked above the hill, the light was very wavy for a few seconds as bands of shadow raced across the front stairs.
     
  18. May 25, 2017 #98

    OmCheeto

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    Interesting. I'd never even heard of them until yesterday. I also see this is the first time they've been mentioned here at PF.
    I watched a few videos, and they are apparently so subtle, that it's difficult for video cameras to capture them.
    And I haven't seen any mention of them except in the context of eclipses. (Though, I only searched for a few minutes.)

    I find the wiki entry on them somewhat hilarious.

    wiki on Shadow Bands;
    "In 2008, Dr. Stuart Eves suggested that shadow bands might be caused by infrasound"

    Professor Brian Jones stated, "The [accepted] theory works; there's no need to seek an alternative."

    The guy in the video I posted yesterday said scientists don't fully understand them.
    But I like NASA's explanation. It seems very reasonable.
     
  19. May 31, 2017 #99

    OmCheeto

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    Whoop! Whoop!

    Solar filter arrived yesterday.

    Test #1:

    2017.05.31.sol.thru.filter.png
    72x zoom.

    Have not a clue why i-Photo thinks that's a face. :olduhh:
     
  20. May 31, 2017 #100

    OmCheeto

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    I'm really glad I bought the 12x12 inch sheet now.

    The sun is REALLY tiny to the naked eye, when you look at it through ISO approved filter media.
    Even looking at it with 7x35 binoculars, it seemed kind of tiny. Though, more jiggly than tiny.

    Note to my fellow old people: Take a chair. A heavily reclining chair. As the eclipse will be VERY high in the sky.
     
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