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

  1. Jun 11, 2017 #126
    Sounds reasonable, and thanks for the source (I saw the earth-solar system etc. timeline table ... - other useful deadlines/timelines on your source too).
    But I mostly meant with a rough calculation, assuming noticable changes on the moon phenomenal diameter, assuming at first stage that the earth is not moving away from the Sun ... (but it does! ...).
    Sounds reasonable too, and it's about of the same order of magnitude as mfb's.
    I agree.
  2. Jun 11, 2017 #127


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    It also doesn't take into account other factors, such as continental drift, which by changing the arrangement of the continents, alters the value of the tidal drag and thus the recession rate of the Moon.
  3. Jun 11, 2017 #128


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    Wow, I think that's pretty amazing that the models are so refined as to make effects that small significant. How big is that effect. ##10^{-1}##? ##10^{-3}##? ##10^{-5}##?
  4. Jun 11, 2017 #129


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    It should be quite significant, as water tides are an important part of the process. Unfortunately it is hard to model that.

    The size of Sun increases over time, this is relevant as well.
  5. Jun 11, 2017 #130
    Furthermore, both moon's recession rate as well as earth's rotation seem to be slowing down over time (with a connection between the two effects).
    E.g. see:

    Note: precise current moon retreat rate: (3.82±0.07) cm/yr
    Last edited: Jun 11, 2017
  6. Jun 13, 2017 #131
    Let's enjoy the total solar eclipses for the next ~600 million years, starting with the one coming up ...
    Yeah, we got time! :smile:
  7. Jun 13, 2017 #132
    I travelled to Penzance in the UK for the August 11 1999 eclipse and it rained!

    I had better luck for the March 29 2006 one in Side,Turkey. We were right on the eclipse track and the BBC team were in the next hotel. Unfortunately dear old Patrick Moore was too ill to attend. I got some great video and stills of the event. I still had time to see it in all its glory despite fiddling with cameras!

    Truly awesome is the only way to describe a total solar eclipse.
  8. Jun 17, 2017 #133
    This one will pass right over me. I'll be out there watching, probably in Gallatin Tennessee, or wherever in the state the best weather is.
  9. Jun 19, 2017 #134


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  10. Jun 21, 2017 #135


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    NASA's Great American Total Solar Eclipse Preview @ 1 pm ET Today
  11. Jun 21, 2017 #136
    1. Science Briefing about the eclipse by NASA (a bit lengthy, but good video):

    2. Interesting and short ... :
  12. Jun 23, 2017 #137
    New & interesting (excellent videos from NASA):
    1. Eclipse Primer on "This Week @NASA" (Today, Fri June 23, 2017):

    2. Ways to watch the Eclipse (came out on 6/21/17):

    3. Safety Briefing (6/21/17):
  13. Jun 23, 2017 #138
    This makes me glad to be living in Salem, I just hope the weather doesn't do anything crazy. :)
    Last edited: Jun 23, 2017
  14. Jun 27, 2017 #139


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    Last edited: Jun 27, 2017
  15. Jun 27, 2017 #140
    I still have my packet of "Science&Telescope" eclipse glasses from the Aug. 11, 1999 eclipse in Europe. Who thinks they are still safe to use them?

    Here's also a couple of short videos from back then:

  16. Jun 29, 2017 #141
    As long as they are not compromised from storage, I would expect them to be just fine.

    If they are torn, creased, or otherwise compromised in the lenses, I would dispose of them, even if they are a souvenir, so that no one in the future (little kids) get a hold of them, and try to use them.

    However, if you have taken care to make sure they made the 18 year journey unscathed, I would expect them to be just fine. On August 22, mine will go into a hard case, and my sock drawer. The 2024 eclipse is only 6-2/3 years, and 90 minutes from home - if I'm alive, I intend to be there with my kids, and (maybe) grand kids.

    If anyone is interested in joining us near Makanda Illinois for an eclipse party, check out the thread at: https://www.physicsforums.com/threads/solar-con-eclipse-road-trip-to-makanda-illinois.914983/
  17. Jun 29, 2017 #142
    Thanks! It makes a lot of sense.
  18. Jul 5, 2017 #143


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    I picked up three pair last week and looked directly at the sun with one yesterday. It appears to work well since I can still see. :smile:
  19. Jul 5, 2017 #144
    That's what I always wear everyday ...
  20. Jul 5, 2017 #145
    Perhaps that explains those nasty bruises on your forehead?... :smile:
  21. Jul 5, 2017 #146
    Gee thanks! ...
  22. Jul 14, 2017 #147
  23. Jul 14, 2017 #148


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    The Concorde did that for more than an hour in 1973.

    An F-22 Raptor could probably stay in the shadow for about an hour as well.
    SR-71 Blackbird could have stayed in the shadow as long as it had fuel, but the model is retired.
  24. Jul 14, 2017 #149
    From the U.T. article.:thumbup:

    Should throw this in also.
    Airborne total solar eclipse chasing goes all the way back to August 19th 1887, when Dmitri Mendeleev (he of the periodic table) observed totality from aloft. There’s a great old video of an effort to chase a 1925 total solar eclipse using the airship the USS Los Angeles:
    Last edited: Jul 14, 2017
  25. Jul 16, 2017 #150


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    This is an fun video:

    I was mostly interested in the "Shadow Bands" discussion.

    ≈4:20 discussion begins about "Shadow bands"

    GMT; "...And if you're really lucky, you'll get to observe shadow bands. The shadow bands don't happen at every eclipse. ..."​

    SED; "How long does it last?"
    GMT; "For about 20 or 30 seconds."

    how to capture shadow bands:
    GMT; "Set up a camera on manual exposure on a king sized white sheet".

    On this last Memorial Day weekend, I went to a garage sale, and purchased TWO king sized white sheets, just for that purpose, for a dollar. (pat on back, pat on back)

    SED: Smarter Every Day, webcaster
    GMT: Gordon M. Telepun: Plastic Surgeon, Eclipse Fanatic, gives talks about "eclipses" at NASA.

    Anyone have any tips on how to capture "low contrast" images with a camera?
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