Contents:
Overview: | Cities (magnitude): | Information: | Weather:| Viewing: | Terms: | Links:

Overview:
The total solar eclipse of August 21 is the first total eclipse visible from America's lower 48 states in over 38 years.
The first to sweep from coast-to-coast in 99 years.
The moon will cover the sun (the umbra or total eclipse) in a path almost 70 miles wide from Oregon to South Carolina.
You will still be able to see the corona around the sun.
It does not become completely dark, but is more like twilight 1/2 hr. after sunset.
It will take about 1 1/2 hours to cross the U.S. starting in OR at 10:16 a.m. PDT and leaving SC at 2:48 EDT.
The duration of totality at the center of the path will range from 2 minutes to 2 min and 40 seconds, it will be shorter as you go to the edge of the path.
The time from when moon first enters the sun until it leaves will range from 2 1/2 hours to almost 3 hours.
The moon will cover 2/3 or more of the sun (the penumbra or partial eclipse) over most of the U.S.

The next total eclipse visible from the U.S. will be in April 2024 visible from Texas to Maine.

A solar eclipse occurs when the moon passes between the sun and earth casting a shadow on the earth.

While the Sun is actually about 400 times larger in diameter than the Moon, the Moon is also about 400 times closer than the Sun. Therefore, the Sun and the Moon appear to be about the same size in our sky.

This single fact explains why we see total solar eclipses - the Moon has an apparent size that just barely covers the Sun completely, yet is not too large that the Sun's atmosphere, its corona, is eclipsed as well.


- Source: EclipseWise.com

Cities (magnitude):
2/3 or more (magnitude > 0.66) of the sun will be covered in most of the U.S.

 



Magnitude
Albuquerque    0.78
Atlanta         0.97
Boston         0.70
Charlotte       0.98
Charlottesville  0.88
Chicago         0.89
Dallas           0.80
Denver          0.93
Houston         0.73
Lake Tahoe      0.84
Los Angeles     0.69
Miami           0.82
Minneapolis     0.86




Nashville      1.02
New York City 0.77
Philadelphia   0.80
Phoenix       0.70
Portland, OR   0.99
Portland, ME   0.67
Saint Louis    1.00
San Antonio   0.69
San Francisco 0.80
San Diego     0.66
San Jose       0.79
Seattle         0.93
Washington DC 0.85


Click on images below for interactive version
   
     Duration: 2:36   Magnitude: 0.80             Duration: 2:37   Magnitude: 0.77 

   
     Duration: 2:51   Magnitude: 0.93             Duration: 2:52   Magnitude: 0.98 
     

 
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Information:
- Begins: Pacific coastline of Oregon at 17:16 UT1 (10:16 am PDT). Totality lasts 1 minute 59 seconds.
The path of totality is 62 - 71 miles wide.
- The time of totality is longest in the center of the path and gets shorter at the edges.
- Maximun duration 2 min. 40 sec. in Kentucky.
- Greatest Eclipse is 20 kilometres northwest of Hopkinsville, KY. Eclipse magnitude here is 1.03 (i.e. it completely covers the sun)
- It passes thru Murphy, in SW North Carolina near the Tennessee border.
- It passes between Greenville and Anderson SC at 19:39 UT1 (2:39 pm EDT)
- The duration from the cities is 2 minutes 11 seconds and 2 minutes 34 seconds, respectively.
- Columbia, SC is to the southeast and has a duration of 2 minutes 30 seconds.
- Just inside the southern limit is historic Charleston. The duration 1 minute 29 seconds.
It moves from 2,200 MPH to 1,500 MPH.

Weather:
See: EclipseWise.com


Viewing:
Warning: Permanent eye damage can result from looking at the disk of the Sun directly, or through a camera viewfinder, or with binoculars or a telescope even when only a thin crescent of the Sun or Baily's Beads remain.

Permanent damage to the retina has been shown to occur in as little as a minute and a half.
In one study when people who stared directly at the sun for several minutes during the 1999 eclipse went to see their doctor, about half had permanent damage.

The moment you begin looking at the sun, you start to develop a sunburn on your the cornea (eyeball), known as photokeratitis.
Symptoms of this condition, Pain that feels like you have dirt in your eye, tearing excessively, redness and an extreme sensitivity to light, usually appear a few hours after the damage has occurred. Exposure for short periods will usually dissipate within 36 hours. ( Gizmodo.com)
Looking at the sun steadily for longer periods can cause damage to the retina, the collection of light-sensitive cells located at the back of the eye. Solar retinopathy, as the damage is known, may not be painful like photokeratitis--but the results can be permanent.

During the short time when the moon completely obscures the sun - known as the period of totality - it is safe to look directly at the star, but it's crucial that you know when to take off and put back on your glasses.
There are several ways to observe an eclipse safely;
Special glasses that meet the ISO 12312-2 safety standard. See below.
Welder's goggles with a rating of 14 or higher. (Warning: Harbor freight flip up welder goggles are only #10)

See:
Looking at the Sun in health here
How long does it take before your eyes get damaged when looking at the sun? | UCSB Science Line
NASA Eye Safety During Solar Eclipses and Eye Safety During a Total Solar Eclipse
What Happens When You stare at The-Sun | Gizmodo.com


Eye protection for observing an eclipse:
Reputable Vendors of Solar Filters & Viewers | American Astronomical Society (AAS)
Paper ISO 12312-2 certified glasses (block out 100% of harmful UV and infrared as well as 99.999% of intense visible light) can be found for $1.00.

Observing Solar Eclipses Safely | mreclipse.com

Listen to the NPR report on eye protection with Ralph Chou, professor emeritus of optometry and vision science at the University of Waterloo, who's a leading authority on eye damage from eclipse viewing.


Terms:
- Eclipse Magnitude is the fraction of the Sun's diameter covered by the Moon at greatest eclipse.
- Greatest eclipse - Greatest eclipse is defined as the instant when the axis of the Moon's shadow cone passes closest to Earth's center.
- Penumbra - The penumbra is the weak or pale part of the Moon's shadow, where the sun is only partially blocked.
- From within the penumbra, the Sun is only partially blocked by the Moon as in the case of a partial eclipse. This contrasts with the umbra, where the Sun is completely blocked resulting in a total eclipse.
- Umbra - The umbra is the darkest part of the Moon's shadow. From within the umbra, the Sun is completely blocked by the Moon as in the case of a total eclipse. In the 2017 eclipse this is 70 miles wide.
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Links:
Solar Eclipse Across America - August 21, 2017 | American Astronomical Society
EclipseWise - Solar and Lunar Eclipses
Eclipse Calculator - Eclipses in USA | TimeandDate.com
2017 Eclipse: Earth, Moon and Sun | Scientific Visualization Studie (SVS), NASA
MrEclipse.com
How to Photograph a Solar Eclipse

Return to Eclipses

last updated 13 Aug 2017