Monday, August 21, 2017: Mark Your Calendar!
For the first time since 1979, a total eclipse of the Sun is coming to the continental United States, and for the first time since 1918, it is crossing the country from coast to coast. Unless you’re a member of the small but growing cadre of “eclipse chasers,” you’ve probably never seen a total solar eclipse before, as they tend to occur in far-flung places requiring costly travel. Not this time. On August 21st the Moon’s approximately 70-mile-wide shadow will cross the U.S. from Oregon to South Carolina, turning day to night for an estimated 12 million people who live within the narrow path of totality. You should make every effort to get into the path too.
| Video introduction to the August 21, 2017, solar eclipse across America. |
Here’s why: During a total solar eclipse, the Moon blocks the Sun’s bright face — the photosphere — briefly revealing our star’s outer atmosphere: the shimmering corona, or “crown.” Made of rarefied gas heated to millions of degrees, with its atoms highly ionized (stripped of electrons), the diaphanous corona gets sculpted into streamers and loops by the Sun’s powerful magnetic field and shines with a light seen nowhere else. It is hauntingly beautiful and, without doubt, one of the most awesome sights in all of nature.
The corona is always there, but we usually can’t see it because the photosphere is about a million times brighter and drowns it out. When the Moon covers the Sun, the corona is definitely the main attraction, but there’s so much more to the experience. At the beginning and end of totality, the thin middle layer of the Sun’s atmosphere, the chromosphere, blazes in an arc of ruby red. The sky darkens to a deep twilight blue, with yellow, orange, and pink sunrise/sunset colors on the horizon in all directions. Bright stars and planets shine forth, and the air temperature drops noticeably. Birds and farm animals, thinking dusk has settled, return to their nests and barns, and bats come out to feed.
Get Yourself into the Path of Totality!
Outside the path of totality all of North America will get a partial solar eclipse. But even a 99% partial eclipse pales in comparison to a total one. It’s like buying a ticket at the box office, standing outside the theater, and saying you’ve seen the show. Most Americans live within a 1- or 2-day drive of totality next August 21st, so with a little advance planning, the experience of a lifetime can be yours.
Depending on your location, the corona will be visible for up to 2 minutes 40 seconds. During those precious moments, it is perfectly safe to look directly at the Sun, even through binoculars or a telescope. But whenever any part of the photosphere is uncovered, it is absolutely essential to view the Sun through a safe solar filter, that is, one that meets the ISO 12312-2 international standard. Such filters are widely available at affordable prices. Looking at the uneclipsed or partially eclipsed Sun through dark sunglasses or any other unapproved filter is a recipe for serious and potentially permanent eye injury. See our Eye Safety and Resource pages for details.
The following pages contain basic information about the August 21, 2017, solar eclipse and about solar eclipses more generally, along with links to more comprehensive information on other trusted websites.