Academic journal article The Science Teacher

New Views of Sun's Corona

Academic journal article The Science Teacher

New Views of Sun's Corona

Article excerpt

The Sun's visible surface, or photosphere, is 10,000 degrees Fahrenheit. As you move outward from it, you pass through a tenuous layer of hot, ionized gas or plasma called the corona. During a total solar eclipse, the corona glimmers ghostly white around the hidden Sun.

A mystery for decades is how the solar atmosphere grows hotter, not colder, the farther you go from the Sun's surface. A rocket mission launched in July 2012 has just provided a major piece of the puzzle.

The High-resolution Coronal Imager, or Hi-C, revealed one of the mechanisms that pumps energy into the corona, heating it to temperatures up to 7 million degrees F. The secret is a complex process known as magnetic reconnection.

"This is the first time we've had images at high enough resolution to directly observe magnetic reconnection," explained Smithsonian astronomer Leon Golub. "We can see details in the corona five times finer than any other instrument."

The Sun's activity, including solar flares and plasma eruptions, is powered by magnetic fields. Most people are familiar with the simple bar magnet, and how you can sprinkle iron filings around one to see its field looping from one end to the other. …

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