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Solar Eclipse 2017: What's happening?

Solar Eclipse 2017: What's happening?

On Monday, August 21, 2017, there will be a solar eclipse. Are you curious what that means and what you should know about viewing the eclipse in our area?

Here's a handy guide to the exciting astronomical event coming up, including:

(Image Credit: NASA Goddard Space Flight Center Visualization Laboratory)

 

Eclipse FAQs

 

Q: What’s happening?

A: In a solar eclipse, the moon gets between the Sun and Earth, so the Moon’s shadow falls on Earth for a short time. Anyone who is in the Moon’s shadow sees the Sun partially or totally covered by the Moon.

 

Q: What will we see from Rochester?

A: A partial eclipse. The Moon will begin to cover the Sun at 1:14pm. At the moment of greatest eclipse, 2:36pm, 70 percent of the Sun will be covered by the Moon. Using a safe solar viewing method, we will see the Sun as a crescent in the sky. After greatest eclipse, the Moon gradually uncovers the Sun. The eclipse ends for Rochester viewers at 3:52pm.

 

Eclipse Diagram  

 

Q: Are eclipses dangerous?

A: Like hiking in the woods, riding a bicycle, or cooking on an outdoor grill, eclipse viewing is safe, enjoyable and worthwhile if you equip yourself with some basic information and take simple precautions. To prevent eye damage, do not look directly at the bright disk of the Sun. (You wouldn’t normally do that anyway, but during an eclipse the Sun is more interesting than usual.) Don’t look into a mirror at a reflected image of the Sun. Instead, look through a filter or “glasses” made specifically for solar viewing, or project the Sun’s image onto some surface. Scroll down for more about safe viewing methods. There are no such things as dangerous rays that come only during eclipses. On eclipse day, RMSC will offer many opportunities for safe solar viewing.

 

Q: Where will this eclipse be total?

A: This eclipse will be total as seen from a 70-mile-wide path of totality that cuts across the continental U.S. from Oregon to South Carolina. Places in the path of totality include Salem and Madras, OR; Boise National Forest; Grand Teton National Park; Jackson and Casper, WY; Grand Island, NE; Lincoln, NE; St. Joseph, MO; part of Kansas City; Columbia, MO; part of St. Louis; Nashville, TN; Greenville and Charleston, SC. As seen from the path, the Sun will be totally covered by the Moon for as long as 2 minutes 40 seconds.

Path of eclipse totality map

 

Q: Where is the closest place to Rochester where totality will be visible?

A: In terms of miles driven by car, the closest part of the path of totality is in central Tennessee. However, there is likely to be traffic congestion leading into the path of totality on eclipse day, adding hours to the trip.

 

Q: Where in our sky will the Sun be at eclipse time? I need to know if a nearby building or tree will block my view.

A: As seen from western New York at mid-eclipse, the Sun will be in the south-southwestern sky, a little more than halfway up from the horizon to the overhead point. Check the Sun’s position between 2pm and 3pm any day between now and eclipse time; the Sun will be in about the same place.

 

Q: When was the last solar eclipse in Rochester?

A: See “Eclipses you might remember,” below. Many people remember an annular eclipse that occurred May 10, 1994. The last time Rochester experienced a total solar eclipse was January 24, 1925.

 

Q: When is Rochester’s next total solar eclipse?

A: There will be a solar eclipse whose path of totality passes over Rochester on April 8, 2024. Totality begins at 3:20pm Rochester time.

 

Q: How rare is this?

A: For Rochester or any other single location, rare; globally, not so rare. There are at least two solar eclipses every year, and there can be as many as five. In many eclipses, the Moon’s shadow passes over the oceans or polar regions, where few people are watching. For most of the others, the Moon’s shadow does not come near Rochester. Jean Meeus, a world-renowned expert on astronomical calculations, found that a random point on Earth sees either a total or annular eclipse on average every 140 years. But that is only an average. The actual timing of eclipses at one location is irregular. For example, Carbondale, Illinois is about to experience two total eclipses just seven years apart (2017 and 2024), then not another one until the twenty-fourth century! See “Websites we recommend” for links to maps of every eclipse from many centuries in the past to many centuries in the future.

 

Q: What is RMSC doing for the eclipse?

A: Four big things! Check out our Eclipse Day page for activities, including:

Kids wearing protective eclipse glasses
 Photo Credit: Mark Margolis/AAS 
  • Safe solar viewing glasses 
    RMSC has sold out, but you may find some at your local library.
  • Special Planetarium show all summer
    A one-hour star show, Eclipses 2017 and 2024, geared for older children and adults, is presented at least six days a week from July 5 through September 9. The best times to see this show are before or after eclipse day, because there will be only one performance on August 21.
  • Museum activities on eclipse weekend
    Friday, August 18 through Monday, August 21, from 11am to 3pm in the Museum building, RMSC presents Exploring Science: Earth and Space! Explore fun hands-on activities, meet local scientists, and connect with current NASA research in heliophysics, Earth and planetary science, and astrophysics.
  • Additional activities on eclipse day, Monday, August 21 Commemorative eclipse postage stampVolunteers from the University of Rochester’s Society of Physics Students present demonstrations from 11am to 3pm. Representatives from the U.S. Postal Service will be here with the new “Total Eclipse of the Sun” stamp that changes with the touch of a finger. You can purchase stamps and get a special commemorative postmark (Photo credit: U.S. Postal Service). More volunteers led by the Astronomy Section, Rochester Academy of Science, will operate telescopes and other viewing devices at three outdoor solar viewing stations around the RMSC campus from 1pm to 4pm. If the sky is cloudy, come in to the Museum building or Planetarium lobby to watch live video from the path of totality on internet screens.

 

Q: I don’t live in Rochester, but I’m in the area. Will the timing of the eclipse be different for me?

A: Not by much. Here, from the trustworthy website eclipsewise.com, are times of the beginning, maximum, and end of the eclipse, and the percentage of the Sun’s disk covered at maximum, for some nearby cities (all Eastern Daylight Time).

Rochester    1:14pm      2:36pm      3:52pm      70%  
Toronto 1:10pm 2:32pm 3:49pm 71%
Buffalo 1:11pm 2:34pm 3:51pm 72%
Corning 1:16pm 2:38pm 3:55pm 72%
Syracuse 1:18pm 2:38pm 3:54pm 68%

 

Safe Solar Viewing Methods

Once again: like hiking in the woods, riding a bicycle, or cooking on an outdoor grill, eclipse viewing is safe, enjoyable and worthwhile if you equip yourself with some basic information and take simple precautions.It is never safe to stare directly at the bright disk of the Sun. Too much of the Sun’s direct light can damage your eyes without your knowing it, because the retina, the part of the eye that detects light, has no pain receptors.

Here are two simple approaches to safe solar viewing:

Looking through specially-made solar filters or “glasses”

Eclipse through the lens protective glassesThe only safe way to look directly at the uneclipsed or partially eclipsed Sun is through special-purpose solar filters, such as “eclipse glasses” (like those for sale at RMSC while supplies last) or handheld solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the Sun.

Check your glasses or viewer for a label saying that the filter material conforms to ISO 12312-2, the international standard for filters for direct observation of the Sun. (Celestron, a reputable maker of telescopes and binoculars, uses a “Solar Safe” logo to represent its compliance with ISO 12312-2.) Some solar viewing filters are black, others are silver in appearance.Here are some materials that are not safe for solar viewing:

  • CDs – not safe for solar viewing
  • Mylar party balloons – not safe for solar viewing
  • Laser show or fireworks glasses – not safe for solar viewing
  • 3D glasses (red-blue or any other kind) – not safe for solar viewing

RMSC has ISO 12312-2-compliant eclipse glasses for sale while supplies last.

Public libraries are another source of eclipse glasses. Over 4800 libraries around the U.S., including over a dozen in the Rochester region, are planning to distribute glasses for viewing programs through the STAR Library Education Network. Here is a map of participating libraries.

(Photo Credit: AAS)

Looking at a projected image of the Sun

Eclipse viewed through a colander shadowAny small hole will project an image of the Sun on a light-colored screen. Try this: use a no.2 pencil point, a knitting needle, or the point on a school compass to poke a hole in a card. That’s your “pinhole.” Hold another card that is white or light-colored (your projection screen) in the shadow of your pinhole card about an arm’s length away. Look for a little circle on the screen. That is an image of the Sun. During the partial eclipse, that circle will become a crescent.

You will probably find the image to be washed out by ambient light from the sky and your surroundings. You can use some kind of box to hold the pinhole at one end and the projection screen at the other end. The box gives shade on the projection screen, making the image easier to see.

Before eclipse day, experiment with different-sized holes and with different distances to the screen. What combination gives you the brightest image? The sharpest image? To make a very small pinhole, try puncturing a small piece of aluminum foil. Then tape that over a bigger hole in cardboard.

If you are in a big, open building, such as a barn, with tiny holes or vents in the roof, look for Sun images on the floor. If the roof is high above the floor, the images will be large and sharp.

A straw hat, kitchen colander, or anything else with many small holes will project a pattern of crescents during the eclipse.

Or, let nature provide the pinholes. Look in the dappled shade under a tree. Tiny gaps between the leaves act as pinholes, projecting many overlapping Sun images on sidewalks and walls. During a partial eclipse those become crescents. You will realize that dappled shade under a tree has always been a combination of thousands of overlapping Sun images!

 

Fun Facts

When pinhole-projected, the size of the Sun’s image will always be about 1/100 of the distance from the pinhole to the surface where you see the image. So, for example, if the surface is 100 inches (about 8 feet) from the pinhole, the Sun’s image will be about 1 inch wide.

The shape of the pinhole doesn’t matter much, as long as the hole is small and not too close to the screen. The hole can be a triangle or a square; it will still make a circular image of the Sun’s disk.

The Sun’s outer atmosphere, called the corona, is safe to look at, but only when the Sun is totally eclipsed. Totality will not happen in Rochester’s sky in the 2017 eclipse, but it will happen in the eclipse on April 8, 2024. 

 

Solar Viewing with Sophisticated Equipment

Experienced amateur and professional astronomers have ways of using telescopes and other equipment to view or project the Sun safely. Telescopes are designed to concentrate light, and concentrated sunlight can be dangerous if not handled knowledgeably. So you may hear about neutral-density filters, Sun stops, hydrogen-alpha filters, and other solar observing technologies. Volunteer amateur astronomers from the Astronomy Section of the Rochester Academy of Science plan to set up a few such devices at RMSC on eclipse day – so you don’t have to! 

Past Eclipses

Here are a few eclipses you might remember (and some related events). 

July 20, 1963 Total solar eclipse. Path of totality ran across Alaska, Canada and Maine. Partial in Rochester.
   
February 26, 1979 Total solar eclipse. Path of totality curved from Washington State up to Hudson Bay. Partial in Rochester.
   
July 11, 1991  Total solar eclipse. Practically nothing to see from Rochester, but total in Hawaii. 
   
May 10, 1994  Annular solar eclipse. Rochester was in the central path. Mid-eclipse was in early afternoon. A big event at RMSC! 
   
December 25, 2000  Partial solar eclipse. About 48 percent of the Sun was covered in Rochester’s sky. 
   
June 8, 2004 and June 6, 2012 Transits of Venus. Not officially called eclipses, but the planet Venus appeared as a small black dot crossing the face of the Sun – a sort of mini-eclipse. 
   
August 21, 2017  Our partial eclipse! 
   
April 8, 2024 Total solar eclipse. Rochester is in the path of totality! 

 

Visit the history section of GreatAmericanEclipse.com for wonderful documents from past eclipses.  

 

Recommended Websites

Still curious? Here are some websites we recommend for more information.

Solar Eclipse Across America from the American Astronomical Society | Eclipse.aas.org
Our recommendation for the best place to start. Comprehensive, easy to use, carefully created by astronomers who are experts on the Sun, eclipses, and observing. There are sections on eye safety, imaging and video techniques, links to other resources, and even special information for government officials and for eye care professionals. 

GreatAmericanEclipse.com
A commercial site created by cartographer Michael Zeiler, with many beautiful maps and a fine section on recent eclipses in history. Especially interesting Zeiler’s maps, based on census data and the U.S. road network, to predict traffic flow and congestion approaching the path of totality. 

Eclipsewise | Eclipsewise.com
Created by Fred Espenak, the astronomer who did eclipse calculations for NASA before he retired. Now he’s still doing eclipse calculations, but at his own website. Here you will find maps of eclipses from centuries in the past to centuries in the future and as much information as you are likely to want on how we know when and where eclipses will occur. Notice the interactive Google map of the 2017 eclipse. Click anywhere on it to see eclipse timings for that location. Mr. Espenak took the photo used on the commemorative eclipse postage stamp being issued this summer by the U.S. Postal Service.

Xavier Jubier’s Interactive Eclipse MapsXavier Jubier is a French engineer who is also a master of eclipse calculation. Here are many beautiful animations and maps, web and phone apps, weather information, and an interactive Google map that generates a little image of the Sun as it appears at mid-eclipse for any location. 

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