Solar eclipse of August 21, 2017

The solar eclipse of August 21, 2017, dubbed the "Great American Eclipse" by some media, was a total solar eclipse visible within a band that spanned the contiguous United States from the Pacific to the Atlantic coasts. It was also visible as a partial solar eclipse from as far north as Nunavut in northern Canada to as far south as northern South America. In northwestern Europe and Africa, it was partially visible in the late evening. In northeastern Asia, it was partially visible at sunrise.

Prior to this event, no solar eclipse had been visible across the entirety of the United States since June 8, 1918; not since the February 1979 eclipse had a total eclipse been visible from anywhere in the mainland United States. The path of totality touched 14 states, and the rest of the U.S. had a partial eclipse. The area of the path of totality was about 16 percent of the area of the United States, with most of this area over the ocean, not land. The event's shadow began to cover land on the Oregon coast as a partial eclipse at 4:05 p.m. UTC (9:05 a.m. PDT), with the total eclipse beginning there at 5:16 p.m. UTC (10:16 a.m. PDT); the total eclipse's land coverage ended along the South Carolina coast at about 6:44 p.m. UTC (2:44 p.m. EDT). Visibility as a partial eclipse in Honolulu, Hawaii began with sunrise at 4:20 p.m. UTC (6:20 a.m. HST) and ended by 5:25 p.m. UTC (7:25 a.m. HST).

This total solar eclipse marked the first such event in the smartphone and social media era in the United States. Information, personal communication, and photography were widely available as never before, capturing popular attention and enhancing the social experience. The event was received with much enthusiasm across the nation; people gathered outside their homes to watch it, and many parties were set up in the path of the eclipse. Many people left their homes and traveled hundreds of miles just to get a glimpse of totality, which few ever get to experience. Marriage proposals were timed to coincide with the eclipse, as was at least one wedding. Logistical problems arose with the influx of visitors, especially for smaller communities. The sale of counterfeit eclipse glasses was also anticipated to be a hazard for eye injuries.

The next solar eclipse that crossed the United States occurred on April 8, 2024 (12 states). Future solar eclipses that cross the United States will occur on August 23, 2044 (3 states), and on August 12, 2045 (10 states). Annular solar eclipses—wherein the Moon appears smaller than the Sun—occurred in October 2023 (9 states) and will occur in June 2048 (9 states).

The total eclipse occurred at the Moon's ascending node of orbit and had a magnitude of 1.0306. Occurring about 3.2 days after perigee (on August 18, 2017, at 14:20 UTC), the Moon's apparent diameter was larger during this eclipse. It was visible within a narrow corridor 70 miles (110 km) wide, crossing 14 of the contiguous United States: Oregon, Idaho, Montana, Wyoming, Nebraska, Kansas, Iowa, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina, and South Carolina. It was first seen from land in the U.S. shortly after 10:15 am PDT (17:15 UTC) at Oregon's Pacific coast, and then it progressed eastward through Salem, Oregon; Idaho Falls, Idaho; Casper, Wyoming; Lincoln, Nebraska; Kansas City, Missouri; St. Louis, Missouri; Hopkinsville, Kentucky; and Nashville, Tennessee; before reaching Columbia, South Carolina about 2:41 pm; and finally Charleston, South Carolina. A partial eclipse was seen for a greater time period, beginning shortly after 9:00 am PDT along the Pacific Coast of Oregon. Weather forecasts predicted clear skies in Western U.S. and some Eastern states, but clouds in the Midwest and East Coast.

The longest ground duration of totality was 2 minutes 41.6 seconds at about 37°35′0″N 89°7′0″W / 37.58333°N 89.11667°W / 37.58333; -89.11667 in Giant City State Park, just south of Carbondale, Illinois, and the greatest extent (width) was at 36°58′0″N 87°40′18″W / 36.96667°N 87.67167°W / 36.96667; -87.67167 near the village of Cerulean, Kentucky, located in between Hopkinsville and Princeton. This was the first total solar eclipse visible from the Southeastern United States since the solar eclipse of March 7, 1970. Two NASA WB-57Fs flew above the clouds, prolonging the observation time spent in the umbra. A partial solar eclipse was seen from the much broader path of the Moon's penumbra, including all of North America, particularly areas just south of the totality pass, where the eclipse lasted about 3–5 hours, Hawaii, Central America, the Caribbean, northern South America, Western Europe, and some of West Africa and Northeast Asia.

At one location in Wyoming, a small group of astronomers used telescopic lenses to photograph the sun as it was in partial eclipse, while the International Space Station was also seen to briefly transit the sun. Similar images were captured by NASA from a location in Washington. (See Gallery – partial eclipse section).

During the eclipse for a long span of its path of totality, several bright stars and four planets were visible. The star system Regulus was almost in conjunction with the Sun. Mars was 8° to the right, and Venus 34° right. Mercury was 10° left, and Jupiter 51° left.