Coronal 'Rain' on The Sun: Clearest View Yet | Big Bear Solar Observatory

Coronal 'Rain' on The Sun: Clearest View Yet | Big Bear Solar Observatory

Coronal rain forms when hotter plasma in the Sun’s corona cools down and becomes denser. Like raindrops on Earth, coronal rain is pulled down to the surface by gravity. Because the plasma is electrically charged, it follows the magnetic field lines that make huge arches and loops, instead of falling in a straight line.

This imagery provides views from a 23-minute time-lapse video comprised of the highest resolution images ever made of coronal rain. Scientists indicate that the strands can be narrower than 20 kilometers.

This imagery was taken by the Goode Solar Telescope at Big Bear Solar Observatory. It shows the hydrogen-alpha light emitted by the solar plasma. The imagery is artificially colorized, yet based on the color of hydrogen-alpha light, and darker color is brighter light. 

The Sun’s corona—the outermost layer of its atmosphere, visible only during a total solar eclipse—has long intrigued scientists due to its extreme temperatures, violent eruptions, and large prominences. However, turbulence in the Earth’s atmosphere has caused image blur and hindered observations of the corona. A ground-breaking recent development by scientists from the U.S. National Science Foundation (NSF) National Solar Observatory (NSO), and New Jersey Institute of Technology (NJIT), is changing that by using adaptive optics to remove the blur.

As published in the journal Nature Astronomy, this pioneering ‘coronal adaptive optics’ technology has produced the most astonishing, clearest images and videos of fine-structure in the corona to date. This development will open the door for deeper insights into the corona’s enigmatic behavior and the processes driving space weather.

Funded by the National Science Foundation (NSF) and installed at the 1.6-meter Goode Solar Telescope (GST), operated by NJIT’s Center for Solar-Terrestrial Research (CSTR) at Big Bear Solar Observatory (BBSO) in California, “Cona”—the adaptive optics system responsible for these new images—compensates for the blur caused by air turbulence in the Earth’s atmosphere—similar to the bumpy air passengers feel during a flight.

“The turbulence in the air severely degrades images of objects in space, like our Sun, seen through our telescopes. But we can correct for that,” says Dirk Schmidt, NSO Adaptive Optics Scientist who led the development.

The 1.6-meter Goode Solar Telescope (GST), is located in Big Bear Lake, California. The steady temperature of the water surface around it helps keep the air around the telescope calm, reducing the optical effects of turbulent air that degrades the telescope’s images of the Sun and that the adaptive optics further removes to achieve the maximum image detail. The GST is the second-largest solar telescope in the world and is home to several instruments that scientists use to analyze physical processes of the Sun.

Credit: Schmidt et al./NJIT/NSO/AURA/NSF

Duration: 18 seconds
Release Date: May 27, 2025

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