Total Solar Eclipse in North America – Path of Totality – NASA/SVS (2017)

During the August 21, 2017 total solar eclipse, the Moon’s umbral shadow will traverse across the North American continent, from Oregon to South Carolina. Transition from west to east coast will last a little over 90 minutes. Along the path of totality, observers will see the Moon completely obscure the Sun for about two and a half minutes.

The math used to calculate the trajectory of the eclipses to create maps such as the one featured here was worked out by Friedrich Wilhelm Bessel and William Chauvenet in the 19th century.

Traditional eclipse calculations assume that all observers are at sea level and that the Moon and Earth are perfectly smooth spheres centered on their centers of mass. This animation shows the umbra and its path by taking elevational changes on the Earth’s surface into account. Moreover the irregular lunar limb (the silhouette edge of the Moon’s disk) is also accounted for. The animation runs at a rate of 30× real time — every minute of the eclipse takes two seconds in the animation. The oblique view emphasizes the terrain of the umbral path.

In the following animation, steps in the shading denote different percentages of Sun coverage (eclipse magnitude), at concentric levels of 90%, 75%, 50% and 25% respectively. The yellow and orange contours map the path of the penumbra. The outermost yellow contour is the edge of the penumbra path. Outside this limit, no part of the Sun is covered by the Moon.

Total Solar Eclipse 2017 in North America – NASA/SVS from Nature Documentaries on Vimeo.

Solar and lunar eclipses that recur every 6,585.3 days (18 years, 11 days, 8 hours) are very similar in their duration, path of totality and obscuration. Scientists call this length of time a Saros cycle. They occur at the same node, that is the Moon’s distance from Earth is appproximately the same, and they happen at the same time of year.

Eclipses have been very important in all Human cultures. Contraptions such as the Antikythera Mechanism were built to predict them in advance with high accuracy. You can check out past and future total solar eclipse events from the NASA’s Solar Eclipse page. A total solar eclipse was recorded in Brazil and Turkey on the same day of March 29th, 2006 by the Sunrise Earth filming crew. The experiential TV series was aired in Discovery Channel.

 

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