The most spec­tac­u­lar thing you will ever see

The Washington Post Sunday - - SUNDAY OPINION - BY JAY PASACHOFF

Tens of mil­lions of Amer­i­cans have an ex­ceed­ingly rare op­por­tu­nity this month. There’s no way I’m go­ing to miss it. How about you? On Aug. 21, a to­tal so­lar eclipse will be vis­i­ble in a band about 65 miles wide stretch­ing from Ore­gon to South Carolina. This will be the first coast-to-coast “to­tal­ity” in the United States in 99 years, though, most re­cently out of the 20th cen­tury’s dozen Amer­ica so­lar eclipses, Hawaii had a to­tal eclipse in 1991 and the Pa­cific North­west had one in 1979. Hav­ing seen 33 to­tal eclipses in my life, I im­plore any­one who can to take ad­van­tage of this ex­pe­ri­ence.

My rea­son for trav­el­ing to see the to­tal eclipse may be dif­fer­ent from yours. For me, it’s a rare op­por­tu­nity to study the corona, a ma­jor part of the sun’s at­mos­phere that can be seen only dur­ing the two min­utes or so of a full eclipse that the moon blots out the so­lar sur­face, pre­vent­ing sun­light from turn­ing the sky blue. No space­craft or Earth-based tele­scope can ob­serve that part of the sun with the qual­ity we get dur­ing an eclipse.

But — as­sum­ing you’re not an as­tronomer — why should you make the same pil­grim­age? It is sim­ply the most spec­tac­u­lar thing you can ever see.

Words can’t do jus­tice to the pri­mal feel­ing of eeri­ness and awe evoked by this ce­les­tial event, but here’s what to ex­pect:

Dur­ing the first hour of par­tial eclipse, which you can ob­serve safely only through spe­cially cer­ti­fied fil­ters avail­able for a dol­lar or two (and free at many li­braries), you wouldn’t know that any­thing spe­cial was hap­pen­ing. But the last 15 min­utes or so bring sharp­en­ing shad­ows, changes in the light, some­times cool­ing winds and a dark­en­ing sky. Faint rip­ples on the ground, known as shadow bands, may cross the land­scape. The most im­pres­sive part is the fi­nal minute: As the sun tran­si­tions from 99 per­cent to to­tal cov­er­age, the sky abruptly gets about 10,000 times darker.

Just be­fore to­tal­ity, at the rim of the sun, a cres­cent of sun­light be­comes bro­ken by moun­tains on the edge of the moon — the so-called Baily’s beads. The last bead gleams so brightly around the moon’s sil­hou­ette, as the sun’s spiky corona be­comes vis­i­ble, that the eclipse looks like a di­a­mond ring in the sky.

At that point, your safety glasses be­come un­us­able, since they are too dark for to­tal­ity. The corona is the same bright­ness as the full moon and is equally safe to look at with the naked eye. All around the moon, the glo­ri­ous corona halo of the sun is vis­i­ble, as are Jupiter and Venus and even a few stars else­where in the sky. The hori­zon glows red from the light out­side the moon’s shadow.

But to see th­ese dra­matic glo­ries, you must travel into the zone of to­tal­ity, which tra­verses parts of 14 states. You should try to get there even if you have to drive many hours. If the sky is clear, you are guar­an­teed to find it worth­while. (If it’s cloudy, the sky will sim­ply get abruptly darker.)

If you’re not in the zone of to­tal­ity, as will be the case for most of the coun­try, the eclipse will be in­tel­lec­tu­ally in­ter­est­ing but not dra­matic. If you look (al­ways through a so­lar fil­ter), per­haps at five- or 10-minute in­ter­vals, you will be able to see that a bite has been taken out of the sun.

Be­cause this eclipse is so ac­ces­si­ble, sci­en­tists have planned dozens of ex­pe­di­tions. My stu­dents, col­leagues and I, with sup­port from the Na­tional Sci­ence Foun­da­tion and the Na­tional Geo­graphic So­ci­ety, are bring­ing some two tons of equip­ment to Ore­gon to cap­ture as much data in our com­put­ers and cam­eras as pos­si­ble in our two min­utes of to­tal­ity.

We hope to learn more about how the sun shines. We want to know how the corona is heated to mil­lions of de­grees and how erup­tions from the sun that im­pact Earth — now known as space weather — are gen­er­ated. The safety of satel­lites in or­bit, power lines on Earth and even pas­sen­gers in air­planes, es­pe­cially those on po­lar routes, may de­pend on our knowl­edge of so­lar erup­tions.

In the past, to­tal eclipses have led not only to the dis­cov­ery of a new el­e­ment — he­lium — but also to the re­al­iza­tion that the corona sur­rounds the sun and not the moon; that Ein­stein’s gen­eral the­ory of rel­a­tiv­ity cor­rectly pre­dicts the dis­place­ment of stars near the sun; and that the outer part of the sun (and there­fore of tril­lions of other stars) is some­how heated to mil­lions of de­grees.

But the most im­por­tant sci­en­tific out­come from this year’s eclipse may be more fun­da­men­tal: in­spir­ing a 7- or 8-year-old girl or boy some­where to en­ter a ca­reer of sci­ence, per­haps even lead­ing to a fan­tas­ti­cally won­der­ful dis­cov­ery 20 or 30 years from now. See­ing the event on a TV or com­puter screen sim­ply won’t do. Our fu­ture sci­en­tists need to see it out­side with their own eyes. It might just be the key to some hith­erto unimag­in­able break­through ben­e­fit­ing all the peo­ple of the world.

Jay Pasachoff is chair of the In­ter­na­tional As­tro­nom­i­cal Union’s Work­ing Group on So­lar Eclipses, a pro­fes­sor of astron­omy at Wil­liams Col­lege and au­thor of the “Peter­son Field Guide to the Stars and Plan­ets.”

SPENCER PLATT/GETTY IM­AGES

Karolyna Landin shows off a pair of so­lar-eclipse glasses at a New York eye­glass store.

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