As we head off to Wyoming to view the total solar eclipse, my husband Bill decided to put into writing the answer to the viewing questions he’s been asked several times a day.
Bill’s quickie guide on how to observe the solar eclipse on Aug 21, 2017:
Partial eclipse only: Check https://eclipse2017.nasa.gov/ or apps for local start and end times and degree of totality (and much more useful information). Use approved paper eclipse glasses with plastic lenses if you want—BUT—the use of pinhole projectors for the eclipse has been underpromoted and, IMHO, is a superior way to follow the progressively waning crescent of the sun as the eclipse progresses. AND, it’s 100% safe and doesn’t require specialized equipment!
A simple piece of aluminum foil with a pinhole through it, or a more sophisticated put-over-your-head box with a pinhole-camera projection in it (get plans from the internet), or even a flat cheese grater(for multiple images) will all work. The sun shines through the little hole and its image is projected onto the ground or a white sheet of paper or whatever you provide, and you can enjoy that projected image without any eye filter—and make it as big as you like. (DO NOT look through the hole or anything like that—it is simply a projection device.) OR, simply go under a tree—the dappled sunlight you are so used to seeing under trees is only pinhole projections of the round sun through overlapping leaves—during an eclipse those dapples turn into crescents!
Partial plus totality: For partial phases, see above. For those going to the path of totality, it helps to learn the contact terminology: First contact, partial eclipse begins, Moon first starts passing in front of Sun, small “bite” appears out of solar disk and slowly grows bigger–Second contact, totality begins, Moon completely in front of Sun, sky goes dark, corona, prominences, and bright planets and stars suddenly appear—Third contact, Sun reemerges from behind Moon, totality ends, daylight returns and corona, etc. suddenly disappear—Fourth contact, Moon moves completely off Sun, partial eclipse ends.
Time between first and second contact is roughly 1.5 hours; time between second and third contact (totality) is between 2 and 3 minutes; time between third and fourth contact, roughly 1.5 hours again.
Wherever you are, learn the times of these contacts (https://eclipse2017.nasa.gov/) and wear a watch that’s accurate.
Viewing totality: Try to get to a spot with an open western horizon so you can see the shadow approaching in the few minutes before totality. At totality, take the eclipse glasses off or turn away from the pinhole projection and look up at the sun with your naked eyes! Better yet, with binoculars or a small telescope—without filters! As long as you can see the corona, your eyes are safe—but be very aware of when totality ends, for at that instant (or before) you must turn your eyes and your optical devices away from the sun.
The end of totality is the epitome of anticlimax—even though the same thing is happening (partial eclipse) that you watched with mounting excitement over the previous hour, you are now emotionally exhausted and ready to pack it up and go home. For this reason, immediately after totality the great exodus will begin and the roads will be jammed.
Good luck everybody!
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