SOME HOT TAKES

Scientists have come up with a host of hypotheses

Magnetic waves

In 1942, Hannes Alfvén said large amounts of energy could be carried by magnetised waves of plasma from the Sun’s surface to the corona along magnetic fields before bursting with heat. The existence of these waves was confirmed in 2021.

Bursts of heat

Tiny eruptions called nanoflares occur in the corona; they are one-billionth the size of normal solar flares. One theory by Eugene Parker says these could be keeping the corona hotter than the surface of the Sun.

Energy transfer

The outer layer of the Sun is in a state of constant turbulence, and it’s known that energy is being transferred outwards from the Sun. But observations show that ions are heated more than electrons, and this theory suggests the opposite would happen.

The helicity barrier

The latest study suggests that low-frequency turbulence is halted by an effect called the helicity barrier which limits electron heating and diverts the energy into ion cyclotron waves, which then causes highfrequency heating.