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Studying total solar eclipses have revealed some of the most fundamental discoveries in science today. 

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During these celestial events, 

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scientists discovered the sun’s structure, 

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the first proof of Einstein’s theory of general relativity, 

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and the element helium – 30 years before it was found on Earth. 

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They also discovered huge solar explosions called coronal mass ejections 

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- eruptions on the sun that continue to be an important component of NASA’s research.

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Coronal mass ejections, or CMEs,

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are giant eruptions made up of hot gas and plasma.

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From the sun’s surface, they propel immense clouds of solar material into space, 

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speeding at up to a million miles per hour 

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and carrying enough energy to power the world for 10,000 years.

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Sometimes, they’re directed towards Earth 

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when they can affect our planet's space environment, causing space weather.

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Scientists track and study CMEs, because 

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they can trigger global changes in Earth’s magnetic field. 

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When intense, these can create magnetic storms that can cause aurora,

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but can also affect satellite electronics and power grids on the ground. 

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Scientists discovered these eruptions in the 1970s

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during the beginning of the modern satellite era 

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– a time when satellites in space 

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were able to capture thousands of images of solar activity 

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that had never been seen before. 

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But, in hindsight, these might not have been

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the first time scientists had noticed these solar features. 

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Soon after they discovered CMEs, 

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scientists came across reports of a total solar eclipse in 1860 

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that looked very similar to their satellite images. 

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On July 18, 1860, the shadow of the moon traveled over North America, 

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Spain, and North Africa before departing Earth.

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Much of the path of totality traveled over populated land

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resulting in a wealth of observations.

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Back then, astronomical photography was still new, 

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so many scientists recorded their observations by hand.

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The drawings show the large white fingers of the corona 

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and also a distinctive arc-like feature. 

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With multiple images drawn from different locations across Europe it appears to evolve over time.

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But not all of the images showed this. 

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About two thirds of people saw the tulip head-like shape, 

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but one third didn’t see anything at all

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including renowned scientist Angelo Secchi. 

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It wasn’t until over 100 years later with regular satellite imagery

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that scientists reopened the debate about what was seen in the 1860 eclipse. 

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The strong resemblance shows that this eclipse may be the first record of a CME.

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While satellites in the space age exploded the field of CME research, 

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total solar eclipses seen from the ground 

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still provide unique views of the sun’s atmosphere 

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that help our understanding of what causes these explosions. 

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Current instruments in space studying the corona

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need to block the sun’s bright body with an occulting disk.

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The disk covers up the sun and a portion of the lower corona 

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- an important region that scientists believe is responsible for accelerating CMEs and forming solar wind.

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So when eclipses happen to fall on land, 

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scientists take advantage of these rare events. 

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With each new total eclipse, there’s the chance for new information and new research 

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-- and the chance to reveal something as astronomical as the first CME. 

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