page_title: Coronal loop
hierarchical_section_title: Coronal loop
caption_attribution_description: Example of solar coronal loops observed by the Transition Region And Coronal Explorer (TRACE), 171&#160;Å filter. These loops have a temperature of approximately 106&#160;K. These loops contrast greatly with the cool chromosphere below.
context_page_description: Coronal loops are huge loops of magnetic field beginning and ending on the Sun's visible surface projecting into the solar atmosphere. Hot glowing ionized gas trapped in the loops makes them visible. Coronal loops range widely in size up to several thousand kilometers long. They are transient features of the solar surface, forming and dissipating over periods of seconds to days. They form the basic structure of the lower corona and transition region of the Sun. These highly structured loops are a direct consequence of the twisted solar magnetic flux within the solar body. Coronal loops are associated with sunspots; the two "footpoints" where the loop passes through the sun's surface are often sunspots. This is because sunspots occur at regions of high magnetic field. The high magnetic field where the loop passes through the surface forms a barrier to convection currents, which bring hot plasma from the interior to the sun's surface, so the plasma in these high field regions is cooler than the rest of the sun's surface, appearing as a dark spot when viewed against the rest of the photosphere.
context_section_description: Coronal loops are huge loops of magnetic field beginning and ending on the Sun's visible surface (photosphere) projecting into the solar atmosphere (corona).  Hot glowing ionized gas (plasma) trapped in the loops makes them visible.  Coronal loops range widely in size up to several thousand kilometers long.  They are transient features of the solar surface, forming and dissipating over periods of seconds to days. They form the basic structure of the lower corona and transition region of the Sun. These highly structured loops are a direct consequence of the twisted solar magnetic flux within the solar body.  Coronal loops are associated with sunspots; the two "footpoints" where the loop passes through the sun's surface are often sunspots.  This is because sunspots occur at regions of high magnetic field.  The high magnetic field where the loop passes through the surface forms a barrier to convection currents, which bring hot plasma from the interior to the sun's surface, so the plasma in these high field regions is cooler than the rest of the sun's surface, appearing as a dark spot when viewed against the rest of the photosphere. The population of coronal loops varies with the 11 year solar cycle, which also influences the number of sunspots.
caption: Typical coronal loops observed by TRACE.
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