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November 17, 2017

This diagram depicts the Earth-sun-moon geometry of a total solar eclipse. Graphic is not to scale. If drawn to scale the Moon would be 30 earth diameters away. The sun would be 400 times that distance. 

Courtesy Photo

Don’t be left in the dark: Safe viewing encouraged during solar eclipse


Tracey Wolfe
Grainger Today Editor
BEAN STATION – It has been 239 years since a solar eclipse occurred solely in the U.S.

According to NASA, the last time that happened was in 1778. The last total eclipse in the U.S. occurred Feb. 26, 1979.

Monday, August 21, areas in Tennessee are in the path of a total solar eclipse. A total eclipse occurs when the moon completely blocks the sun and the sun’s tenuous atmosphere, the corona, can be seen. The zone of totality during the eclipse will cover an area of the United States from Oregon to South Carolina.

While not in the zone of totality, those in Grainger County will experience a partial eclipse. The partial eclipse will begin in Grainger County at approximately 1:05 p.m. The maximum eclipse will be reached at approximately 2:35 p.m. and the end of the partial eclipse will be reached at approximately 4 p.m.

According to NASA, “during a total solar eclipse, the normal rhythms of Earth are disrupted. The sudden blocking of the sun makes the day appear to be night in more ways than just the loss of light.  The temperature drops and plants and animals react as if it is dusk – birds can be seen flying home to settle in for sleep in the middle of the day.”

Those who plan to observe the eclipse, whether traveling to an area within the zone of totality or observing the partial eclipse locally, are encouraged to only directly view the eclipse through solar filters, such as eclipse glasses. Viewing the sun can be dangerous if the proper precautions are not taken. Failure to use proper observation methods could result in permanent eye damage or severe vision loss. Because the moon blocks much of the sun during an eclipse, it is possible to look at the sun without it being as uncomfortable as usual. Even with the sun almost completely covered by the moon, the visible sun is bright enough to burn the retinas of the eye.

NASA offers these tips for viewing the solar eclipse:

  • Always inspect solar filters before use; if scratched or damaged, discard it. Read and follow any instructions printed on or packaged with the filter.
  • Always supervise children using solar filters.
  • Stand still and cover both eyes with eclipse glasses or solar viewer before looking up at the bright sun. After looking at the sun, turn away and remove the filter — do not remove it while looking at the sun.
  • Do not look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars or other optical device.
  • Similarly, do not look at the sun through a camera, a telescope, binoculars or any other optical device while using eclipse glasses or hand-held solar viewer — the concentrated solar rays will damage the filter and enter the eye(s), causing serious injury.
  • Seek expert advice from an astronomer before using a solar filter with a camera, a telescope, binoculars or any other optical device. Note that solar filters must be attached to thefrontof any telescope, binoculars, camera lens or other optics.
  • Those who are within the path of totality should remove solar filters only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright sun begins to reappear, replace the solar viewer to look at the remaining partial phases.
  • Outside the path of totality, observers mustalwaysuse a safe solar filter to view the sun directly.
  • Anyone who normally wears eyeglasses should keep them on. Put eclipse glasses on over them, or hold a handheld viewer in front of them.

 

Eclipse glasses or viewers should be compliant with the ISO 12312-2 safety standard. It is vital those viewing the eclipse protect their eyes from possible permanent damage. Those viewing the eclipse should not stare continuously at the sun, and should take breaks to give their eyes a rest.

Sunglasses, even those with very dark lenses, should not be used for viewing the eclipse. While welders glass of a sufficiently high number is considered safe for viewing the solar eclipse, only those with a shade of 12 or higher are considered adequate. Those who choose to use a welders glass to view the eclipse must ensure the filter is a Shade 12 or higher or they risk damage to their eyes. It is also not safe to look at the sun through the viewfinder of a camera or an unfiltered telescope. Everyone is encouraged to protect their eyes during the solar eclipse.

With about 200 million people in the U.S. living within a day’s drive of the path of totality, traffic congestion throughout the U.S., particularly in areas within the path of totality, is expected. The Federal Highway Administration (FHA) is referring the solar eclipse as “a planned special event for which there had been no recent precedent in the United States.” FHA has made the following recommendations for drivers who are traveling to view the eclipse:

  • Don’t stop along the interstate or park on the shoulder during the event.
  • Exit the highway to a safe location to view and/or photograph the eclipse.
  • Don’t take photographs while driving.
  • Don’t try to wear opaque eclipse glasses while operating a vehicle.
  • Turn headlights on – do not rely on automatic headlights when the eclipse blocks out the sun.
  • Watch out for pedestrians along smaller roads. People may be randomly parking and walking alongside the roadside in the hours around the eclipse to get the best view.
  • Prepare for extra congestion, especially on the interstates in the path the day before, day of and day after the eclipse.
  • Avoid travel during the eclipse or in the area of the main path if possible.
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