High temperature of the Sun's Solar corona gives it unusual spectral features, which led some in the 19th century to suggest that it contained a previously unknown element, "coronium".
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12 Facts About Solar corona
2.
Sun's Solar corona is much hotter than the visible surface of the Sun: the photosphere's average temperature is around compared to the Solar corona's 1 to 3 million kelvin.
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3.
The Solar corona is 10 times as dense as the photosphere, and so produces about one-millionth as much visible light.
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4.
The Solar corona is separated from the photosphere by the relatively shallow chromosphere.
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5.
The exact mechanism by which the Solar corona is heated is still the subject of some debate, but likely possibilities include induction by the Sun's magnetic field and magnetohydrodynamic waves from below.
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6.
However, during the Sun's active periods, the Solar corona is evenly distributed over the equatorial and polar regions, though it is most prominent in areas with sunspot activity.
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7.
Electromagnetic radiation from the Solar corona has been identified coming from three main sources, located in the same volume of space:.
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8.
Coronal heating problem in solar physics relates to the question of why the temperature of the Sun's corona is millions of kelvins greater than that of the surface.
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9.
NASA's Parker Solar corona Probe is intended to approach the Sun to a distance of approximately 9.
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10.
Waves in plasmas are notoriously difficult to understand and describe analytically, but computer simulations, carried out by Thomas Bogdan and colleagues in 2003, seem to show that Alfven waves can transmute into other wave modes at the base of the Solar corona, providing a pathway that can carry large amounts of energy from the photosphere through the chromosphere and transition region and finally into the Solar corona where it dissipates it as heat.
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11.
The magnetic field in the solar corona must undergo nearly constant reconnection to match the motion of this "magnetic carpet", so the energy released by the reconnection is a natural candidate for the coronal heat, perhaps as a series of "microflares" that individually provide very little energy but together account for the required energy.
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12.
Idea that nanoflares might heat the Solar corona was proposed by Eugene Parker in the 1980s but is still controversial.
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