Emission in EUV: The coronal loops are observed in specific EUV wavelengths emitted by highly ionised atoms in the solar corona, such as iron (Fe) and neon (Ne). These emissions are characteristic of the temperatures and densities found in coronal loops.
Morphology: The coronal loops exhibit distinct shapes and structures, including arcades, fan loops, and helmet streamers. These structures are consistent with the magnetic field configurations and plasma dynamics in the corona.
Time evolution: Coronal loops show dynamic behaviour, evolving over time. They can form, grow, shrink, and dissipate over periods ranging from minutes to hours. This time evolution is consistent with the evolution of magnetic structures and plasma flows in the corona.
Observational techniques: Coronal loops are observed using advanced imaging instruments onboard solar spacecraft, such as the Solar Dynamics Observatory (SDO) and the Interface Region Imaging Spectrograph (IRIS). These instruments provide high-resolution images and spectroscopic data that allow scientists to study the physical properties and dynamics of coronal loops in detail.
Confirmation from other observations: Coronal loops are also observed in other wavelengths, including X-rays, visible light, and radio waves. These observations provide complementary information and further support the existence of coronal loops as physical structures.
In summary, coronal loops are not optical illusions but rather real features of the Sun's magnetic atmosphere. They are composed of hot, magnetised plasma, and their emission, morphology, time evolution, and observational techniques all confirm their existence as physical structures in the Sun's corona.
