The Sun's outermost atmospheric layer, extending millions of kilometers into space and visible as a shimmering halo during total solar eclipses. Despite being farther from the Sun's core, it reaches temperatures of over 1 million degrees Celsius.
From Latin 'corona' meaning 'crown' or 'garland,' referring to its crown-like appearance around the Sun during eclipses. The term has been used since ancient times, though the corona's true nature as a super-heated atmospheric layer wasn't understood until the 20th century.
The corona is one of the universe's greatest mysteries - it's somehow 200 times hotter than the Sun's surface, which is like finding that the air around a campfire is hotter than the fire itself! This 'coronal heating problem' has puzzled scientists for decades, and the Parker Solar Probe is currently flying through the corona to solve this mystery.
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