The corona is made up of loops of hot gas that arch high above the Sun’s surface. These loops can have a wide range of temperatures, many reaching several million degrees Kelvin. This illustrates some of the various wavelengths and temperates SDO can observe. The picture was taken on July 9, 2012 and once you reach the chromosphere, you can start seeing those coronal loops.
The coronal loops are found around sunspots and in active regions. These structures are associated with the closed magnetic field lines that connect magnetic regions on the solar surface. Many coronal loops last for days or weeks but most change quite rapidly.
Some loops, however, are associated with solar flares and are visible for much shorter periods. These loops contain denser material than their surroundings.
Credit: NASA SDO