The western sky darkens, air temperatures drop, birds and animals become suddenly quiet. Almost instantly, daylight is transformed into deep twilight, as Venus and the brighter stars appear. Incredibly, where the Sun stood sits a black disk surrounded by a pearly white halo with delicate, spiky streamers extending outward in all directions. You’re experiencing a total solar eclipse.
It’s been a long wait since 1979, but a total solar eclipse is finally returning to the contiguous United States. On Monday, August 21, the moon’s dark, umbral shadow will reach the coast of Oregon. In the next hour and a half, the shadow will speed across parts of Oregon, Idaho, Wyoming, Nebraska, several mid-western and southeastern states, leaving the US near Charleston, South Carolina. The path of this total eclipse is narrow, nowhere wider than 73 miles. But all of the U.S. will experience at least a partial eclipse on August 21. From west-central Colorado about 85% of the sun will be covered by the Moon, with maximum eclipse occurring around 11:42 a.m. So isn’t 85% good enough? Many people say: No – definitely not! If you see only a partial eclipse, you’ll have missed the most amazing sight, the beautiful solar corona. The corona is the Sun’s atmosphere, where charged particles are propelled into space at speeds that can exceed one million miles per hour. From the Earth’s surface, the wonder of the corona is visible only during the brief minutes when an eclipse becomes total.
Never observe the partial phases of a solar eclipse directly without proper eye protection. Staring at the Sun directly can result in severe eye damage and even blindness. Safe solar filters or image projection must be used to observe the partial phases of a solar eclipse. Be aware that partial phases will make up more than 98% of the eclipse’s duration, even if you travel to the path of totality. If you are staying on the Western Slope, you can join rangers at Black Canyon of the Gunnison National Park’s South Rim to view the partial eclipse with “eclipse glasses” and safe solar telescopes.
Western Slope Skies is produced by members of the Black Canyon Astronomical Society. This episode was written & recorded by Art Trevena.
Links of interest for the August 21, 2017 solar eclipse: