Corona is not just the name of the virus that has caused the ongoing pandemic. It is also what scientists call the upper atmosphere of the Sun. The Sun’s corona has carried an age-old mystery within. The temperature of the Sun’s blazing surface is about 5,500 degrees Celsius but if you go far away from the surface to the giant fireball’s outer atmosphere, weirdly, the temperature reaches more than 1 million degrees Celsius.
This logic-defying mystery has been a pain for astronomers for years. However, in 1942, a Swedish scientist Hannes Alfvén came up with a theory that was debated for years before it was tentatively accepted. A recent study has finally found proof of the existence of Alfvén waves, a phenomenon defined by Alfvén in his explanation of the 150-year-old mystery. According to Alfvén, if electricity conducting liquids -the Sun’s plasma — are placed in a constant magnetic field — the Sun’s atmosphere, they could carry energy electric currents capable of transferring energy over very large distances. Alfvén waves are oscillations of ions and the magnetic field in a plasma. These oscillations can cause the Sun’s plasma to rise up to the corona and crash, depositing its energy there, like a heat bomb.
The latest study, published in Nature Astronomy on May 10, validates the 80-year-old theory of Alfvén waves. The study found the existence of these oscillations in a magnetic pore in the photosphere, the lowest layer of the Sun’s atmosphere.
On April 29, NASA’s solar probe spacecraft Parker reached the closest to the Sun, within a record distance of 10.4 million kilometres. Launched in August 2018, Parker Solar Probe is aimed to fly through Corona itself to gather more clues about the Sun’s balming atmosphere. The recent study used Interferometric Bidimensional Spectropolarimeter, a device for solar observation used in a solar telescope such as the National Solar Observatory in New Mexico, US.