Solar Eclipse of 21 August, 2017

[trysail]

https://eclipse2017.nasa.gov/sites/default/files/eclipestages.png



https://eclipse2017.nasa.gov/sites/default/files/globe_inset_v3.png


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[trysail]

On August 21, 2017, a total solar eclipse will cross the contiguous United States for the first time since 1918...



Q: How are eyes damaged by staring at the sun?

A: Solar retinopathy is a result of too much ultraviolet light flooding the retina. In extreme cases this can cause blindness, but is so painful that it is rare for someone to be able to stare at the sun for that long. Typically, eye damage from staring at the sun results in blurred vision, dark or yellow spots, pain in bright light or loss of vision in the center of the eye (the fovea). Permanent damage to the retina has been shown to occur in ~100 seconds, but the exact time before damage occurs will vary with the intensity of the sun on a particular day and with how much the viewer's pupil is dilated from decongestants and other drugs they may be taking. Even when 99% of the Sun's surface (the photosphere) is obscured during the partial phases of a solar eclipse, the remaining crescent Sun is still intense enough to cause a retinal burn. Note, there are no pain receptors in the retina so your retina can be damaged even before you realize it, and by then it is too late to save your vision!

-NASA
https://eclipse2017.nasa.gov/faq
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[Freudian_Slit]

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[Freudian_Slit]

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[Freudian_Slit]

https://electrek.files.wordpress.com/2017/01/swansons-law.png?w=633&h=475

 

[trysail]

...The last total solar eclipse viewed from contiguous United States was on Feb. 26, 1979 whose path passed through the northwestern U.S. states of Washington, Oregon, Idaho, Montana, North Dakota, and Canadian provinces of Saskatchewan, Manitoba, Ontario and Quebec. After the August 2017 total solar eclipse, the next annular solar eclipse that can be seen in the continental United States will be on October 14, 2023 which will be visible from Northern California to Florida. Following this, we will have a total solar eclipse on April 8, 2024 visible from Texas to Maine...


Q: Why do eclipse tracks move eastward even though the Earth rotates from west to east?

A: Because the Moon moves to the east in its orbit at about 3,400 km/hour. Earth rotates to the east at 1,670 km/hr at the equator, so the lunar shadow moves to the east at 3,400 – 1,670 = 1,730 km/hr near the equator. You cannot keep up with the shadow of the eclipse unless you traveled at Mach 1.5







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[trysail]

Q: When will the next transits of Mercury and Venus occur during a total solar eclipse?


A: The last transits of Venus occurred on June 8, 2004 and June 5, 2012, with the next pair predicted for December 10, 2117 and December 8, 2125. Transits of Mercury are much more common, with the most recent one occurring on May 9, 2016 and the next one on November 11, 2019. It is not unreasonable to ask when we might expect such transits to occur during the time of a total solar eclipse. The next anticipated simultaneous occurrence of a solar eclipse and a transit of Mercury will be on July 5, 6757, and a solar eclipse and a transit of Venus is expected on April 5, 15232.
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[trysail]

Q: What is a Saros Cycle?

A: A Saros Cycle is approximately 6585.3211 days, or 18 years, 11 days, 8 hours in length. One saros period after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, a near straight line, and a nearly identical eclipse will occur. The Moon will have the same phase and be at the same node and the same distance from the Earth. In addition, because the saros is close to 18 years in length (about 11 days longer), Earth will be nearly the same distance from the sun, and tilted to it in nearly the same orientation (same season). Given the date of an eclipse, one saros later a nearly identical eclipse can be predicted. Each total solar eclipse track looks similar to the previous one, but is shifted by 120 degrees westward. The August 21, 2017 total solar eclipse is part of the Saros 145 series. The previous total solar eclipse in this series occurred on August 11, 1999. The next one will be on September 2, 2035. The first cycle in this series occurred on January 4, 1639, and the last one will be on April 17, 3009.



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[trysail]

Three (3) Conditions Necessary For A Total Solar Eclipse...

I. There has to be a new moon...
II. The moon has to cross the plane of Earth’s orbit...
III. The moon has to be near [its perigee]...



...When the totality hits Oregon, it will be moving at 2,955 mph...It will slow down to 1,462 mph as it passes through Kentucky. Then it will speed back up to 1,502 mph by Charleston, South Carolina...​

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[trysail]

Why Future Earthlings Won't See Total Solar Eclipses

..."So actually for billions of years you can have a total eclipse, but this very evenly matched eclipse, where it is barely total, that happens for a relatively short amount of time,"...
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[4est_4est_Gump]

I guess I'm lucky.

We're in the middle of the path of totality not too far from the point of greatest duration.



Will it destroy my phone if I take pics?

Will I harm my eyes viewing those pics?

 

[trysail]

Q: If the dark side of the moon has to be facing the Earth for a solar eclipse to occur, why don’t we have them every new moon?

A: Because the moon’s orbit isn’t perfectly matched up with the Earth’s.

It’s tilted 5 degrees, like so:

https://cdn.vox-cdn.com/thumbor/mJh-KlLJq_-63mSg1TGNe9WjYXI=/800x0/filters:no_upscale()/cdn.vox-cdn.com/uploads/chorus_asset/file/8890867/Screen_Shot_2017_07_21_at_11.27.44_AM.png
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For most new moons, the moon’s shadow completely misses the Earth.

(No one is completely sure why — but it might have to do with how the moon was likely formed: from a massive object smashing into Earth.)
[see: http://www.nature.com/nature/journal/v539/n7629/full/nature19846.html?foxtrotcallback=true ]

Basically, this means during most new moons, the shadow misses Earth.


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[milehighcityman]

Great post Trysail. When I was a little kid and solar eclipses were explained, I wondered the same thing: why don't they occur every new moon. It took a while for the explanation to sink in. LOL.

I am going up to Wyoming to see it at a friends ranch right in the path of totality. Can't wait.

 

[phrodeau]

http://www.mlive.com/weather/index.ssf/2017/08/solar_eclipse_cloud_forecast_s.html

Cloud cover forecast. Don't get caught under a dense collection of water droplets.

 

[trysail]

Q: ...What if I miss the eclipse?

A: Despair not. There will be solar eclipses visible from parts of the contiguous U.S. on Oct. 14, 2023, and April 8, 2024. The one in 2024 will be a total solar eclipse visible from Texas to Maine...



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[4est_4est_Gump]

Yeah, we have five days of rain forecast.


There's a chance that being in the right location,

Might be at the wrong time...

I was in the right church,

But it must have been the wrong pew!

 

[LIVINRFANTASIES]

Denny

Thanks trysail

 

[trysail]

https://eclipse2017.nasa.gov/sites/default/files/the_sun_1.jpg


Q: What Is the Corona?

The corona is the outer atmosphere of the sun. It is made of tenuous gases and is normally hiding in plain sight, overwhelmed by the bright light of the sun’s photosphere. When the moon blocks the sun’s face during a total solar eclipse, the corona is revealed as a pearly-white halo around the sun. To study the corona, scientists use special instruments called coronagraphs, which mimic eclipses by using solid disks to block the sun's face. During a natural total eclipse, however, lower parts of the corona can be seen in a way that still cannot be completely replicated by current technology.

Eclipse observations are important for understanding why the sun’s atmosphere is 1 million degrees hotter than its surface, as well as the process by which the sun sends out a constant stream of solar material and radiation, which cause changes in the nature of space and may impact spacecraft, communications systems, and orbiting astronauts.​

A: What Is the Chromosphere?

The chromosphere is a thin layer of the sun’s atmosphere that lies just below the corona, and about 3,100 miles (5,000 km) above the photosphere. It is only visible during total solar eclipses or with sophisticated telescopes. The word comes from chromo—or “color”—for the way this layer appears during eclipses: a thin, crimson ring around the edge of the sun, in contrast with the darkened moon and pearly-white corona.​

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[trysail]

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[Fala]

August 21'st is the day I married the man of my life.

We'll have to celebrate under the stars.

We'll report back on the event.

editator adds that we've been married 35 years already.

 

[4est_4est_Gump]

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I'm BLIND!!!

 

[trysail]

Will the lights go out?

...During the eclipse, hundreds of thousands of buildings — both residential and commercial — that normally count on rooftop solar will need to switch to grid power instead.

Add that to the loss from big utility-scale solar farms and California will need to fill a power gap equal to what six million homes use.

"Luckily, we had a really good water year this year," Lyon says. "So we'll have some pretty good flexibility on the hydro." That wasn't the case during the past few summers, when reservoirs were low due to the drought.

What hydropower dams can't make up, natural gas power plants will...
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https://apps.npr.org/dailygraphics/graphics/kqed-eclipse-power-20170815/assets/kqedscience_solar_desktop.jpg

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[JohnnySavage]

I've never been there, but I'm pretty sure California suffers the loss of solar at night. Three hours once every few decades should be manageable.

 

[4est_4est_Gump]

The sun never sets on the Progressive Empire.

 

[trysail]

...There’s a point in the orbit where the moon is farthest away from the sun, and where it’s closest. For a total eclipse to occur, the moon needs to be near its closest approach to Earth.

Eclipses can [also] occur when the moon is at apogee (its farthest distance from the Earth), but the moon won’t block out the entire sun. These are called “annular” or “ring of fire” eclipses, because a white-hot band of sun will encircle the darkened face of the moon. They look cool...


https://cdn.vox-cdn.com/thumbor/esbJQsFfK8HLdAfEHVEtuaTMWsY=/800x0/filters:no_upscale()/cdn.vox-cdn.com/uploads/chorus_asset/file/8886545/144916840.jpg
An annular solar eclipse on May 21, 2012, in Tokyo, Japan. Photo by Masashi Hara/Getty Images
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