Why the Sun's atmosphere is hotter than its surface
A layer beneath the Sun’s surface, acting as a pan of boiling water, is thought to generate a small-scale magnetic field as an energy reserve which, once it emerges from the star, heats the successive layers of the solar atmosphere via networks of mangrove-like magnetic roots and branches. So what source of energy can heat the atmosphere and maintain it at such high temperatures? The scientists also discovered that a structure resembling a mangrove forest appears around the solar mesospots: tangled ‘chromospheric roots’ dive into the spaces between the granules, surrounding ‘magnetic tree trunks’ that rise up towards the corona and are associated with the larger-scale magnetic field. Thin plasma jets near the tree trunks are also produced and are associated with recently discovered spicules. The researchers found that the energy fluxes of their mechanisms match those required by all studies to maintain the temperature of the plasma in the solar atmosphere, namely 4,500 W/m2 in the chromosphere and 300 W/m2 in the corona.