These “Type II” spicules shoot upward at high speeds, often in excess of 60 miles per second (100 kilometers per second), before disappearing.
Credit: NASAīut In 2007, De Pontieu and a group of researchers identified a new class of spicules that moved much faster and were shorter lived than the traditional spicules. Solar spicules as imaged by NASA's Solar Dynamics Observatory. Over the years, experts have proposed a variety of theories, and as De Pontieu said, the spicule theory had been dismissed when it was found spicule plasma did not reach coronal temperatures. And, he said, you’d want to know why it appears the solar atmosphere is breaking all kinds of thermodynamic laws. Solar physicst and former Universe Today writer Ian O’Neill (and current Discovery Space producer, and of Astroengine fame) compared the anomaly of the Sun’s atmosphere being hotter than the surface to if the air surrounding a light bulb was a couple of magnitudes hotter than the bulb’s surface. “Heating of spicules to millions of degrees has never been directly observed, so their role in coronal heating had been dismissed as unlikely,” says Bart De Pontieu, the lead author and a solar physicist at LMSAL. But a good look with new “eyes” reveals a new kind of spicule that moves energy from the Sun’s interior to create its hot outer atmosphere. The existence of these small, narrow jets of plasma, called spicules has long been known, but they had never been directly studied before and were thought to be too cool to have any appreciable heating effect.
But now, using the combined visual powers of NASA’s Solar Dynamics Observatory and Japan’s Hinode satellite, scientists have made direct observations of jets of plasma shooting off the Sun’s surface, heating the corona to millions of degrees. For years researchers have known – and wondered why – the Sun’s outer atmosphere, or corona, is considerably hotter than its surface. The mystery of the Sun’s corona may finally be solved.
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