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

  1. Aug 15, 2017 #221

    BillTre

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    Here is an XKCD comic of the eclipse:
    [​IMG]

    Here is the map referred to (from this site):
    eclipse.png

    Here is another interesting map from the same article:
    Screen-Shot-2017-08-01-at-10.26.41-AM.jpg
     
  2. Aug 15, 2017 #222

    jim hardy

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    I will likely end up near Perryville Missouri. Looks far enough from civilization to be not overrun, but all the motels are booked.
     
  3. Aug 15, 2017 #223

    OmCheeto

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    :oldlaugh:

    2017.08.15.pf.bring.water.png

    I've been camping, in various forms, since 1979. (Actually, since ≈1962, but other people were in charge back then.)

    I just dug out my 3 gallon water jug, that I'm pretty sure I haven't used in 25 years.
    It took 20 minutes in the shower, to scrub off all the petrified cobwebs.

    ps. Found this list on the internet the other day. I think it is mostly accurate.

    16 things to have in your car for a solar eclipse road trip
    1. A full tank of gas [Duh!]
    2. Extra auto fluids {???]
    3. Mobile phone and car charger [Still don't have one.]
    4. Maps (the paper kind) [Is GPS supposed to go out? Guessing this is a "I-phone" thing.]
    5. Extra cash (the paper kind) [This is a VERY GOOD idea, if going to a 300, about to become 10 million, populated rural area]
    6. Extra medication [Goes without saying.]
    7. First-aid kit [I was going to ixnay this, until I almost cut the end off my finger yesterday. OUCH! Band Aids!®]
    8. Basic toolkit [Still thinking about this. Do I bring all my tools?]
    9. Duct tape [I have a full roll, standing by, and ready]
    10. Work gloves [Hadn't thought of that]
    11. Jumper cables [I'm not bringing mine to jump my vehicle. Solar!]
    12. Flashlight with extra batteries ["extra batteries" for your cameras. See my: "My batteries went dead" post]
    13. Spare tire or flat kit [Probably a good idea]
    14. Emergency flares or reflectors [In standstill traffic?]
    15. Water [Non-fluoridated, of course]
    16. Food [Canned. ps. don't forget your can opener! And a spoon!]​
     
  4. Aug 15, 2017 #224

    OmCheeto

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    ps. They forgot "coffee"

    Did that one camping trip, many years ago.
    Almost got married that day.

    Long story.

    snip!
     
  5. Aug 15, 2017 #225

    tony873004

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    Here's a simulation that shows how the sizes of the Moon and Sun change over time as viewed from Earth's center

    Notice how difficult it is to get a total eclipse in December or January when the Sun is large.

    Simulation (runs in your browser): http://orbitsimulator.com/gravitySim...nMoonSize.html
     
    Last edited: Aug 16, 2017
  6. Aug 16, 2017 #226

    mfb

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    In the 21st century, we have 67 total eclipses (list), or 5.6 per calendar month on average.

    Jan: 5 <- perihelion Jan 3
    Feb: 0
    Mar: 6
    Apr: 7
    May: 7
    Jun: 3
    Jul: 6 <- aphelion Jul 4
    Aug: 12
    Sep: 8
    Oct: 1
    Nov: 3
    Dec: 9

    The Moon has to cross the ecliptic at the same time as new moon for an eclipse, this leads to about two "eclipse seasons" per year. They shift around over time, however, with a period of 18.6 years, or -20 days shift per year. This year it is in late February/August, next year in early February and July/August, in 2019 in early January/July and then late December, 2020 in June/December and so on. Typically we get one solar eclipse and one or two lunar eclipses per season, in rare cases we get two solar eclipses, but then they are both partial, and only visible from far north/south, respectively.

    Overall this leads to a roughly uniform distribution of eclipses, with a small bias towards the summer for total eclipses where the Sun appears smaller today, and a small bias towards the winter for partial eclipses. The position of the perihelion relative to the seasons has a period of ~23,000 years, or just 1.5 days per century, too small to be notable over a human lifetime.

    By the way: If you want to be as close to the Sun as possible, 2020 is your opportunity. Kilimanjaro or maybe some place in the Indian ocean, 5th of January around 8 am GMT. The closest perihelion this century.
    If you want to be as far away as possible: 4th of July 2019, around 8 am GMT, probably somewhere south-east of Hawaii.
     
  7. Aug 16, 2017 #227
    my local weather forecast (Washington DC) says partly sunny on 8/21 eclipses day, will keep finger crossed
     
  8. Aug 16, 2017 #228

    OmCheeto

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    Duh....

    https://www.greatamericaneclipse.com/

    Upper right hand image link.
    TODAY'S CLOUD COVER PREDICTION FOR AUGUST 21ST COURTESY OF WDTINC.COM, ESRI.COM, AND GREATAMERICANECLIPSE.COM. GET HI-RES FORECAST MAPS AT THIS LOCATION.

    hmmmm......


    ...for the rest of the nation. Lot's more black! Less traffic for me!


    Today is the first time in 5 days we have not been overcast in the hours before 1 pm.
    (The only time I can do solar PV experiments.)
    [expletives deleted] trees........
     
  9. Aug 16, 2017 #229
    Relax guys! It will be seen getting dark anyway! ... during the day, which is the amazing part. No clouds can do that.
     
  10. Aug 16, 2017 #230

    Janus

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    I've already experienced that once, in '79. This time I hope to actually see more.
     
  11. Aug 16, 2017 #231
    I sure hope so too! Seeing the Sun's corona during totality is of course amazing and unique! It's also a big opportunity to study better and more effectively the sun's activity during that time (e.g. flares etc.) ...

    But if clouds get on the way ... at least we ought to see the "bright side" of daytime darkness! ... Or a video from high altitude totality, or different location. [Personly, I consider nice videos equally as spectacular! ...]

    I guess we'll find out in a few days.
     
    Last edited: Aug 16, 2017
  12. Aug 16, 2017 #232
    Will direct sun damage camera lenses?
     
  13. Aug 16, 2017 #233
    I think, during totality, no.
     
  14. Aug 16, 2017 #234
    What about before? Especially concerning a GoPro.
     
  15. Aug 16, 2017 #235
    I don't think that should be a problem either, as long as you limit appropriately the exposure time (don't keep it too long).
    However, let's wait for more responses to your question (from more people), because I am not a cameras expert.
    [I recall taking short exposure pictures of direct sun at different times and with different types of cameras (even a video) with no problem at all ... just there's not much to see on a bright sun. But on the eclipse it would still be interesting.]
     
    Last edited: Aug 16, 2017
  16. Aug 16, 2017 #236

    russ_watters

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    Yes, it will almost certainly damage the camera without the appropriate filter
     
  17. Aug 16, 2017 #237

    russ_watters

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    A Go-pro, like many modern digital cameras, especially video cameras, doesn't have an active shutter. Exposure is controlled electronically. So this logic will not save the camera.

    Also, a go-pro without a giant lens attached is too low of a magnification to see the eclipse anyway.

    I expect an awful lot of people are going to destroy their cameras on Monday.

    When I was in high school for the 1994 eclipse, I successfully took a photo with a film camera and no filter. The focal length was 900mm and if I remember correctly I traced and cut out a dime on my lens cap, for a focal ratio around 50.
     
  18. Aug 16, 2017 #238
    Even with short exposure time?
     
  19. Aug 16, 2017 #239

    russ_watters

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    Not sure if you saw my last post after posting this, but; No shutter = infinite exposure time

    [Edit] And even on my SLR, with shutter, I'd be worried about melting the shutter.
     
  20. Aug 16, 2017 #240
    We posted ~simultaneously. Ok I get it now. I think you're right.
     
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