Puzzle Page #6: Coronium

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Today's Puzzle Answer: Coronium

During the 1869 total solar eclipse, astronomers Charles Augustus Young and William Harkness observed an unusual green emission line in the Sun's corona, or outer atmosphere. The scientists suspected they had found a new element, which they named "coronium," after its discovery site in the Sun's corona.

Seventy years later, physicist Bengt Edlén proved that the light came from iron that had been ionized, or heated up enough to allow some of its electrons to escape. To emit that light, an iron atom had to lose 13 of its 26 electrons. Achieving such high levels of ionization required temperatures around 1.8 million degrees Fahrenheit — nearly 200 times hotter than the Sun's surface. This discovery led to one of the most enduring mysteries in solar physics: the coronal heating problem.

Learn more about the coronal heating problem.

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