Solar corona puzzle cracked

A solar mystery known for decades may have finally been cracked by three Indian astrophysicists, who solve the puzzle with the help of the available data from Murchison Widefiled Array (MWA).

• The Sun’s corona is the outermost part of the Sun’s atmosphere. The corona is usually hidden by the bright light of the Sun's surface.
• That makes it difficult to see without using special instruments. However, the corona can be viewed during a total solar eclipse.
• During a total solar eclipse, the moon passes between Earth and the Sun. When this happens, the moon blocks out the bright light of the Sun.
• The glowing white corona can then be seen surrounding the eclipsed Sun.
• The corona reaches extremely high temperatures. However, the corona is very dim. The corona is about 10 million times less dense than the Sun’s surface.
• This low density makes the corona much less bright than the surface of the Sun.

How does the corona cause solar winds?

• The corona extends far out into space. From it comes the solar wind that travels through our solar system.
• The corona's temperature causes its particles to move at very high speeds. These speeds are so high that the particles can escape the Sun's gravity.

The mystery

• The corona’s high temperatures are a bit of a mystery. Astronomers have been trying to solve this mystery for a long time.
• The corona is in the outer layer of the Sun’s atmosphere—far from its surface. Yet the corona is hundreds of times hotter than the Sun’s surface.

Highlights of the observation

• The scientists have likened the flashes to smoking guns of small magnetic explosions, which according to the researchers, is the first evidence of its existence.
• They have discovered tiny flashes of radio light emanating from all over the Sun.
• These radio lights or signals result from beams of electrons accelerated in the aftermath of a magnetic explosion on the Sun.
• These weak radio flashes are ‘smoking guns’ or the evidence for the same and hence bring us closer to explaining the coronal heating problem.
• These observations were the strongest evidence till date that the tiny magnetic explosions, originally referred to as ‘nanoflares’ by eminent American solar astrophysicist Eugene Parker, can indeed be heating up the corona (the aura of plasma that surrounds the sun and other stars).

About Murchison Widefield Array (MWA)

• The Murchison Widefield Array (MWA) is the world’s newest telescope, built in Western Australia as part of the worldwide Square Kilometre Array (SKA) network. 
• The MWA is located 315km northeast of Geraldton at the Murchison Radio-astronomy Observatory, a “radio quiet” area larger than Tasmania.
• Within this area, radio transmissions are strictly restricted and monitored, making it one of the quietest places in the world – perfect for carrying out radio astronomy.
• The main objective of the MWA are to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the sun, the heliosphere, the Earth’s ionosphere, and radio transient phenomena, as well as map the extragalactic radio sky.