
The most accurate map for August 21’s total solar eclipse - cyanbane
https://nasaviz.gsfc.nasa.gov/12458
======
gmiller123456
Best advice I've accumulated so far:

1\. Don't plan to drive anywhere on eclipse day (90% of the US lives within an
8hr drive of totality, so traffic will be horrible)

2\. A 600-800mm lens is optimal for photography. Anything short of 200mm is
useless.

3\. Don't make any solid plans until 3-4 days before. Most places only have
about 40% chance of it being clear.

4\. If you're photographing the partial phases. Stop and check everything
(batteries, memory card, focus, etc) about 5 min before totality.

5\. If you have any technological issues during totality, just sit back and
enjoy watching it.

6\. On eclipse day, if you're in a place that has 2 min or more of totality,
just stay there. There's not a lot to be gained by risking moving.

7\. All across the US, the sun will be high in the sky, good horizons aren't
necessary.

~~~
overdunk

      90% of the US lives within an 8hr drive of totality, so traffic will be horrible
    

Oh, come on. Less than 5% of America actually cares enough about astronomical
events to drive 30 minutes to see something. Much less book a hotel stay.

August 21st is a Monday afternoon, so how many employed Americans are going to
ask for the day off, to drive 8 hours, with a 200mm telephoto lens or
telescope?

If totality is the size of several counties, and lasts even ten minutes, how
many people will be on the road within an hour of the event? Lunchtime (or
even all day long) traffic is probably nothing even terrible in 40 out of 50
states. In totality states, traffic won't even compare to a sporting event.

~~~
mudil
Totality lasts ~2 minutes

~~~
overdunk
You are correct, sir. And thinking about OP's statement a little more, maybe
staying off the road is a good idea in the sense that a two minute eclipse can
distract drivers on the road.

But in general, unless you happen to glance at the sun in your field of view
during the eclipse, it's all the darkness of passing clouds for most of the
country.

Are traffic accidents statistically affected by proximity to a total eclipse
of the sun?

------
jessriedel
Can someone explain why the claimed shadow of the moon is vastly more bumpy
than it ever appears in the night sky? Or how to square this with the fact
that altitude of the highest and lowest points on the Moon differ by less than
20km, or less than 1% of the diameter? The shadow looks like it has bumps of
about 5-10% of the diameter.

~~~
Dave_Rosenthal
The diameter of the path of totality is only about 100 miles, because it's
only the umbra of the shadow. This is 20x smaller than the moon diameter. But,
a 1km moon bump is a 1km bump on the umbra as well, magnifying it's effect by
the mentioned 20x and leading to a much different appearance.

~~~
jessriedel
I hadn't thought about this effect! You're absolutely right. Thanks very much.

(For others:) A diagram of the umbra makes this clear:

[https://c.tadst.com/gfx/750x500/total-solar-eclipse-
com.png?...](https://c.tadst.com/gfx/750x500/total-solar-eclipse-com.png?1)

If you draw a few triangles, you can get an analytic expression.

------
dugmartin
If you want to experience the greatest duration plan a trip to Southern
Illinois (more info about duration here:
[https://www.greatamericaneclipse.com/illinois/](https://www.greatamericaneclipse.com/illinois/)).

As a bonus a friend of mine's family winery has booked Ozzy to "bark at the
moon" during the eclipse: [http://loudwire.com/ozzy-osbourne-headlining-
moonstock-solar...](http://loudwire.com/ozzy-osbourne-headlining-moonstock-
solar-eclipse-festival/)

~~~
joezydeco
Most of the Carbondale area was booked solid months ago. There may be some
campsites open but not much else.

I'm staying in St Louis the night before and then picking a direction to drive
based on weather. I don't think it's worth all the hassle to get to southern
Illinois just to get 3 more seconds of totality.

This map will show you how much totality you can experience, unlike the NASA
charts.

[http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017...](http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017_GoogleMapFull.html)

~~~
dionidium
I'll be in St. Louis for this, too. I'm thinking about viewing it from here:

[https://mostateparks.com/event/64121/solar-eclipse-
showdown](https://mostateparks.com/event/64121/solar-eclipse-showdown)

~~~
joezydeco
I've been trying to scout out some open areas away from civilization, mostly
to avoid ambient light but also to avoid huge traffic in and out of any park
or freeway interchange.

I fully anticipate traffic to be screwed up for hours afterward.

~~~
dionidium
I could be totally wrong, but I just don't see it, at least not down there in
Jefferson County. That's not a densely populated area. It's over an hour's
drive from Downtown St. Louis. [0]

I have to say, though, I'll probably leave earlier that morning than I'd
originally planned, because of the comments in this thread.

[0] [https://goo.gl/maps/bJRKJndLnQG2](https://goo.gl/maps/bJRKJndLnQG2)

------
idlewords
If you've never seen a total eclipse before and you live in the US, make every
effort to see this one! It's not something that you can get the feel of by
viewing photos or video. Watching the sun get eaten by a black void activates
something deep inside the animal brain. Don't settle for a partial eclipse, do
what it takes to get in the path of totality.

If you have seen a total eclipse before, then you don't need any convincing.

~~~
baursak
> Watching the sun get eaten by a black void activates something deep inside
> the animal brain.

I was planning to have my 5 year old son see it. But now I wonder whether it
will have any traumatic effect on him.

~~~
mnm1
You would seriously let your son miss this because of some hypothetical
traumatic event that might happen? I feel really bad for him if that's the
case.

~~~
bigiain
I don't think you worded this very well (which is probably why you're getting
down votes), but I agree with your sentiment. This is 100% not something you
should shield children from in my opinion - it's a very rare opportunity to
see something quite magical - even when you know exactly what's going on.

------
Stratoscope
Here are my viewing tips, based on my experience in the 1979 eclipse in
Oregon.

You can photograph the eclipse, but you will have a much grander experience if
you don't try. Photography is just a distraction from the awesome spectacle of
the eclipse, including the phenomena that happen on the ground.

There will be plenty of other people taking great photos, so enjoy those after
the eclipse. A total eclipse, viewed directly with your own eyes, is truly an
experience of a lifetime. No photograph comes close.

Contrary to one or two other comments, eye protection is not necessary _during
totality_ and will prevent you from seeing the full beauty of the corona. It
is perfectly safe to view the _total_ eclipse with the naked eye, or even with
binoculars. Only the partial phases need eye protection (and they definitely
do). [1] [2] [3]

In fact, on the hillside we ended up at, something interesting happened. Most
of the people wore dark sunglasses and faced _away_ from the sun during the
first partial phase, in order to get their eyes a bit acclimated to the dark.
The partial eclipse isn't very interesting compared to totality, and the fun
stuff at that point is happening on the ground: there are ripples of light
dancing on the ground like you see on the bottom of a shallow stream. And you
may get to see the shadow rushing toward you at 10,000 miles an hour!

The moment it reached totality, there were shouts of "it's total!" up and down
the hill. Everyone took off their sunglasses and looked directly at the total
eclipse. Many of us brought binoculars and viewed the corona with them.

The danger is that it is tempting to keep looking at the end of totality, when
the string of beads starts to appear at the edge of the moon (where the sun is
starting to peek through the moon's valleys), and finally the "diamond ring"
where a larger part of the sun appears through the deepest valley. If you
bring proper eye protection, switch to it the moment the string of beads
appear, and definitely before the diamond ring appears! I recommend doing this
after totality and not before, so you don't interfere with your eyes' dark
adaptation before totality.

[1]
[https://eclipse.gsfc.nasa.gov/SEhelp/safety.html](https://eclipse.gsfc.nasa.gov/SEhelp/safety.html)

[2] [https://eclipse.aas.org/resources/telescopes-
binoculars](https://eclipse.aas.org/resources/telescopes-binoculars)

[3]
[http://www.eclipse2017.org/2017/what_you_see.htm](http://www.eclipse2017.org/2017/what_you_see.htm)

~~~
gravypod
> Except during totality, when the Sun's bright face is completely blocked by
> the Moon, it is never safe to look directly at the Sun through a telescope
> or binoculars. During the partial phases of the eclipse, you must secure a
> special-purpose solar filter over the front of your optics before aiming at
> the Sun.

That's a quote from one of the links. Most people will not be in totality.
Most people will only be seeing a partial eclipse. The shaded in line from
this [1] image is where totality will happen.

Most people watching the eclipse will need some form of eye wear.

[1] -
[https://nasaviz.gsfc.nasa.gov/vis/a010000/a012400/a012458/us...](https://nasaviz.gsfc.nasa.gov/vis/a010000/a012400/a012458/usa_eclipse_map_16x9_1920x1080_1024x576.jpg)

~~~
Stratoscope
Yes, my comment was addressed specifically to those who will be viewing the
total eclipse, not the partial eclipse. That's why I emphasized _total
eclipse_ and _totality_.

But thank you for making it more clear that viewing any other kind of eclipse
- partial or annular - requires proper eye protection!

------
smnscu
Smarter Every Day just posted a great video related to this:

> HOW TO WATCH THE ECLIPSE (AND SHADOW SNAKES) - Smarter Every Day 171

[https://www.youtube.com/watch?v=qc7MfcKF1-s](https://www.youtube.com/watch?v=qc7MfcKF1-s)

~~~
ythn
I'm hoping the masses take to capturing high definition footage of the shadow
snakes. Someone, somewhere will be able to get decent footage hopefully.

------
gagabity
What about the rest of the world!!

~~~
pcl
This eclipse will only be visible in totality within the US. Here's a broader-
scale map:

[http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017...](http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017_GoogleMapFull.html)

~~~
joezydeco
This map is way more useful than NASA's. Highly recommended.

------
rbritton
Some tips for photographing it: [http://www.nikonusa.com/en/learn-and-
explore/a/tips-and-tech...](http://www.nikonusa.com/en/learn-and-
explore/a/tips-and-techniques/how-to-photograph-a-solar-eclipse.html)

Solar filters: [https://www.bhphotovideo.com/c/buy/solar-photography-
filters...](https://www.bhphotovideo.com/c/buy/solar-photography-
filters/ci/34576/N/3537148334)

~~~
hellbanner
Won't it just be.. black?

~~~
geerlingguy
It will if you don't pop off the solar filter during the totality! I'm
planning on practicing with the solar timer app mentioned by Smarter Every
Day; I'm not moving anywhere since I'm in the path of totality (for 1:16!), so
I want to make sure I have all the timing down for the little transitional
bits, so I can gun off a dozen or so pictures at any of those moments.

I'll also have a timelapse camera set up on a wider angle (incorporating my
yard, some trees, the sky, etc.) using pi-timelapse[1]

[1] [https://github.com/geerlingguy/pi-
timelapse](https://github.com/geerlingguy/pi-timelapse)

------
wyldfire
I heard from a co-worker who plans to travel to Oregon that some of the hotel
rooms in the path of the umbra are sometimes > 2-3k USD for the night(s) prior
to the eclipse.

~~~
JPKab
I think Oregon is a bad spot to view it. The weather (yes, even in summer) is
too unpredictable and it's too close to populated coastal areas.

Wyoming is the way to go, or western Nebraska. Don't expect to get hotels, but
camping on a rancher's land is easy, and the arid climate in the summer
minimizes chances of cloud cover.

~~~
jasode
_> , or western Nebraska._

I'll be in eastern Nebraska (Omaha) and will drive south on I-80 towards the
eclipse path and hopefully pull off to the side and park somewhere.

What's hard to plan for is whether too many other Nebraskans will have the
exact same idea which means I have to camp out a ridiculous 12 hours before
the event to secure a spot -- or give up entirely.

~~~
ant6n
I'm planning to drive up north from Denver, the day of. Kind of concerned
about how many people will have the same idea, and how early I should start...

~~~
JPKab
I'm in Denver area too. The question is this:

How much better is a 100% eclipse vs. a 90% eclipse that we'll get here?

Is it worth the trip to Wyoming? I think so, but not positive.

~~~
BenjiWiebe
According to everything I've read, and all pictures I've seen, 99% is one
thing, and 100% totally something else.

------
alkonaut
I don't want to travel to this one if I can avoid it, and there seems to be
none in Europe in my life time.

Will the April 2024 one be as good as this one? I suppose one drawback of that
one is that april is probably(?) much larger risk of clouds in a lot of the
US, than august?

[https://www.timeanddate.com/eclipse/list-total-
solar.html](https://www.timeanddate.com/eclipse/list-total-solar.html)

------
teeray
If you want a laugh, mute the audio track of the video on that page and play
the Game of Thrones Main Title instead.

------
gravypod
Hello everyone. I'm currently working with a group who plans to do some
experimental sounding of the effects of the eclipse on the ionosphere. If you
want to learn more about this project please check out our website
[http://hamsci.org/](http://hamsci.org/). We are pushing a number of fun ways
to get involved with collecting very useful data for scientific analysis.

I'd like to ask anyone who lives on the midwest or east coast to consider
helping these projects:

1\. EclipseMob: [http://hamsci.org/node/148](http://hamsci.org/node/148)

This project will ship you a set of ICs and a breadboard that will make up a
VLF receiver. No soldering is required. It's a great kit to put together with
children.

After you build up the kit you plug it into your phone's microphone jack and
run an app that agregates radio signal information (I/Q data I think) to the
EclipseMob organizers. After the eclipse is over you'll still be in possession
of a fully capable VLF receiver kit. You can use it to listen to VLF signals
that are interesting. This may include human generated traffic or whistlers.

2\. Total Eclipse SEQP: [http://hamsci.org/seqp](http://hamsci.org/seqp)

If you have an amateur radio license and want to help participate in a contest
you can hop on the air and operate during the eclipse. The more people on the
air the better dataset we have.

3\. Setup a Reverse Beacon Network receiver.

The main dataset we use is the Reverse Beacon Network. It's a set of automated
receivers that listen to short-wave Morse code and RTTY communications. If you
have a few bucks burning a hole in your pocket and want to set up a we have a
page that talks about how to do this: [http://hamsci.org/cw-reverse-beacon-
network-how-guide](http://hamsci.org/cw-reverse-beacon-network-how-guide)

Using these data sources we would like to generate a very high resolution
picture of the effects of a solar eclipse. As it turns out we don't exactly
have the best understanding of what goes on during an eclipse.

We have a few other projects in the works that I'm not very familiar with. One
idea is recording I/Q data from JT65 bands and building a data set via Zenodo
so that everyone who contributes to the data set gets their name as a
reference on papers that use it.

If you're interested and want to hear more about this you can reply to this
post or send me an email to my "work" email. My email username is jk369 and my
university's mail address is njit.edu.

------
marvin
Regarding weather, places that have clouds due to convection have a chance of
clearing up during the eclipse. I experienced this in China in 2009 -
completely overcast two hours before totality, clearing up just in time due to
lower solar insolation and less convection.

You shouldn't count on this, try positioning for good weather in advance
regardless, but just keep it in mind so you don't crash your car heading for
better weather if things look poor.

------
spcelzrd
My first thought: how will this affect traffic.

I've been in Atlanta too long.

~~~
matthewmcg
Me too.

We were going to make a weekend trip out of this. But we realized the chances
of bad weather are pretty high at our planned viewing site in Western North
Carolina and that it would be better to stay in Atlanta closer to an
Interstate Highway so we can quickly drive to an alternate site.

~~~
eclipsePrepper
It might be difficult to predict a clear sky. Because of hot, summer humidity,
The eastern US has a pretty good chance of afternoon thunderstorms during the
time of the eclipse.

------
corpMaverick
When was the last time an eclipse like this happened in the US ?

~~~
cjensen
It depends what you mean by "like this."

The last US West Coast to US East Coast eclipse was 1918.

The last time the totality was entirely within the current US borders and
never over land elsewhere was 1257.

[https://en.wikipedia.org/wiki/Solar_eclipse_of_August_21,_20...](https://en.wikipedia.org/wiki/Solar_eclipse_of_August_21,_2017)

------
Merad
Question for those who know more than I do about this. According to [0] the
sun will be about 97% obscured at my house. Is it worth traveling for that
last 3%?

0:
[http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017...](http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017_GoogleMapFull.html)

~~~
ytNumbers
I'm no expert, but YES!! Drive the miles to get to 100%. There is absolutely
no comparison between 99% and 100%. They're just totally different beasts.

------
hellbanner
What do the black circles mean?

------
skbohra123
Just wondering, how much is this going to cost into the loss of electricity
generation from the Solar plants across US.

~~~
campers
You should find this article interesting! [https://qz.com/973684/california-
will-lose-enough-solar-ener...](https://qz.com/973684/california-will-lose-
enough-solar-energy-to-power-los-angeles-during-the-eclipse-on-aug-21/)

------
BatFastard
Do you get the full eclipse effect anywhere inside of the green line? Is there
an advantage to being at the red line?

~~~
bradleyjg
The closer to the red line the longer you'll get totality. But anywhere in the
green lines you'll have some period of totality.

The interactive map:
[https://eclipse2017.nasa.gov/sites/default/files/interactive...](https://eclipse2017.nasa.gov/sites/default/files/interactive_map/index.html)

will tell you exactly when and for how long you'll get totality anywhere along
the route.

~~~
BatFastard
Thanks! That is a much better map than original article.

------
brewdad
So what will be the practical difference between 99.4% (at my home) and 100%
about 35 miles away. Is it worth the effort to travel to the true totality
zone? I do unfortunately have a commitment that day, that I cannot avoid,
about 2 hours before the max obscuration passes by.

~~~
LeifCarrotson
35 miles seems small enough to not worry about it - it's just a half hour
drive! It's still months away, I'd hope you could reschedule that conflict.

I have several hundred miles if I wanted to go to the totality zone. But I'm
still curious what it will look like in the difference of 100% vs 82% at my
home.

~~~
tzs
Well, one difference is that if you go to where there is totality you can look
with the naked eye once totality is achieved. If you are in a place where it
is only partial, most experts recommend only looking through filters or via
pinhole projection.

------
martinald
What affect is this going to have on solar power? California has a load of
solar going on, and this may cause a complete collapse in solar output very
suddenly (way more suddenly than the evening). Can peaker plants come up
quickly enough?

~~~
eclipsePrepper
On a hot August summer day, LOTS of power will be lost. It's recommended to
turn off your A.C. to help prevent blackouts and the prevent use of more
expensive natural gas power.

[https://qz.com/973684/california-will-lose-enough-solar-
ener...](https://qz.com/973684/california-will-lose-enough-solar-energy-to-
power-los-angeles-during-the-eclipse-on-aug-21/)

------
brightball
Pretty cool that it's going to pass directly over Clemson, SC. Literally
almost dead center. (2:53 mark of the path video).

------
hellbanner
Are these safe to view? I thought these would be black. Another link talks
about "getting eye protection"?

~~~
Symbiote
Eye protection is essential.

There was a total eclipse in Britain when I was a child [1], and everyone
bought special protective glasses to wear.

Mine were like the paper red-green "3d" glasses you used to get, but with a
black film that was close to opaque. They worked fine.

[1]
[http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_1999...](http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_1999_GoogleMapFull.html)
("Britain" is exaggerating, but we were in Cornwall on holiday.)

------
teekert
* The most accurate map for Aug 21, 2017's total solar eclipse _for north America_ (nasa.gov)

------
BatFastard
Why would they use a tif format for the downloadable map? I haven't seen a tif
format in 10 years.

~~~
bhandziuk
lossless format (potentially) that everyone can open?

~~~
BatFastard
After looking at the map, I can't imagine why a lossless format is required. I
just exported in as a jpg, and it would take a magnifying glass to see the
difference. And the jpg was 16/7% the size (at 90%). Waste of government
bandwidth.

~~~
ceejayoz
I'd imagine NASA's more concerned with pixel perfect reproductions than your
average government agency, given the sort of imagery they're often working
with.

------
leblancfg
Would love to hear how they generated the shadow contours from the Moon to the
Earth's surface!

~~~
dekhn
it's projection geometry. You create a geometry object with the earth's
surface shape. Another with the moon's surface shape. Then, a light source
that emits from a sun's shape. All objects are placed at the appropriate
distances, and made to rotate and translate through space according to normal
orbits.

Then, you project the light from the sun onto the earth, with the moon in-
between. This creates the 2D shape on the earth's surface corresponding to the
shadow.

I've set up something very similar to this in Blender, although its floating
point precision was too low, so I had to fudge things a bit.

~~~
leblancfg
Thanks dehhn. From the LRO picture in the article, you can see that they're
actually taking high-precision elevation maps of both the Moon and Earth into
consideration, which sounds like something rather computationally intensive. I
might be wrong, but I don't think they used Blender to handle that.

I would be curious to hear what tool they actually use, their pipeline, etc.

~~~
rootbear
To the best of my knowledge, it was animated in Maya and rendered with Pixar's
Renderman. When I was in that group, we used IDL to do any elaborate
calculations needed, and then imported the data into Maya/Renderman. This is
exactly what Hollywood does when they have to render a scene that requires a
lot of simulation. I can ask Ernie if he used anything special for this
production.

~~~
leblancfg
That's amazing, thanks so much. Ernie, if you're reading this, great job :)

------
jayess
Times in UTC would be more helpful.

~~~
ComputerGuru
Not for an event where the total eclipse will only be visible in the
continental US. The map in TFA changes timezones so that local time is always
used. It's the same as flight schedules where takeoff and ETA are always
represented in local time.

