Home » “Raindrops in the Sun’s Corona”: New Adaptive Optics Shows Stunning Details of our Star’s Atmosphere
Release Date: May 27, 2025
Scientists from the U.S. National Science Foundation National Solar Observatory and New Jersey Institute of Technology produced the finest images of the Sun’s corona to date. To make these high-resolution images and movies, the team developed a new ‘coronal adaptive optics’ system that removes blur from images caused by the Earth’s atmosphere. Their ground-breaking results were recently published in Nature Astronomy and pave the way for deeper insight into coronal heating, solar eruptions, and space weather, and open an opportunity for new discoveries in the Sun’s atmosphere.
Scientists develop new optical system that removes blur over fine-structure in the Sun’s corona, revealing clearest images to date
BOULDER, CO, Tuesday, May 27, 2025 – 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 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.
Most Detailed Coronal Images to Date Revealed
Funded by the 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.
Among the team’s remarkable observations is a movie of a quickly restructuring solar prominence unveiling fine, turbulent internal flows. Solar prominences are large, bright features, often appearing as arches or loops, extending outward from the Sun’s surface.
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This image of a prominence above the solar surface is a snapshot of a 4-minute time-lapse movie that reveals its rapid, fine, and turbulent restructuring with unprecedented detail. The Sun’s fluffy-looking surface is covered by “spicules”, short-lived plasma jets, whose creation is still the subject of scientific debate. The streaks on the right of this image are coronal rain falling down onto the Sun’s surface. This image was taken by the Goode Solar Telescope at Big Bear Solar Observatory using the new coronal adaptive optics system Cona. The image shows the hydrogen-alpha light emitted by the solar plasma. The image is artificially colorized, yet based on the color of hydrogen-alpha light, and darker color is brighter light. Credit: Schmidt et al./NJIT/NSO/AURA/NSF
A second movie replays the rapid formation and collapse of a finely structured plasma stream. “These are by far the most detailed observations of this kind, showing features not previously observed, and it’s not quite clear what they are,” says Vasyl Yurchyshyn, co-author of the study and NJIT-CSTR research professor. “It is super exciting to build an instrument that shows us the Sun like never before,” Schmidt adds.
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This image was taken by the Goode Solar Telescope at Big Bear Solar Observatory using the new coronal adaptive optics system Cona. The image shows the hydrogen-alpha light emitted by the solar plasma. The image is artificially colorized, yet based on the color of hydrogen-alpha light, and darker color is brighter light.
Credit: Schmidt et al./NJIT/NSO/AURA/NSF
A third movie shows fine strands of coronal rain—a phenomenon where cooling plasma condenses and falls back toward the Sun’s surface. “Raindrops in the Sun’s corona can be narrower than 20 kilometers,” NSO Astronomer Thomas Schad concludes from the most detailed images of coronal rain to date, “These findings offer new invaluable observational insight that is vital to test computer models of coronal processes.”
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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, which make huge arches/loops, instead of falling in a straight line.
This image is a snapshot from a 23-minute time-lapse video which is comprised of the highest resolution images ever made of coronal rain. The scientists show in the paper that the strands can be narrower than 20 kilometers.
This image was taken by the Goode Solar Telescope at Big Bear Solar Observatory using the new coronal adaptive optics system Cona. The image shows the hydrogen-alpha light emitted by the solar plasma. The image is artificially colorized, yet based on the color of hydrogen-alpha light, and darker color is brighter light.
Credit: Schmidt et al./NJIT/NSO/AURA/NSF
Another movie shows the dramatic motion of a solar prominence being shaped by the Sun’s magnetism.
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This image of a solar prominence is a snapshot of a 19-minute time-lapse movie showing how plasma “dances” and twists with the Sun’s magnetic field.
This image was taken by the Goode Solar Telescope at Big Bear Solar Observatory using the new coronal adaptive optics system Cona. The image shows the hydrogen-alpha light emitted by the solar plasma. The image is artificially colorized, yet based on the color of hydrogen-alpha light, and darker color is brighter light.
Credit: Schmidt et al./NJIT/NSO/AURA/NSF
A Breakthrough in Solar Adaptive Optics
The corona is heated to millions of degrees–much hotter than the Sun’s surface–by mechanisms unknown to scientists. It is also home to dynamic phenomena of much cooler solar plasma that appears reddish-pink during eclipses. Scientists believe that resolving the structure and dynamics of the cooler plasma at small scales holds a key to answering the coronal heating mystery and improving our understanding of eruptions that eject plasma into space driving space weather—i.e., the conditions in Earth’s near-space environment primarily influenced by the Sun’s activity (e.g., solar flares, coronal mass ejections, and the solar wind) that can impact technology and systems on Earth and in space. The precision required demands large telescopes and adaptive optics systems like the one developed by this team.
The GST system Cona uses a mirror that continuously reshapes itself 2,200 times per second to counteract the image degradation caused by turbulent air. “Adaptive optics is like a pumped-up autofocus and optical image stabilization in your smartphone camera, but correcting for the errors in the atmosphere rather than the user’s shaky hands,” says BBSO Optical Engineer and Chief Observer, Nicolas Gorceix.
Since the early 2000s, adaptive optics have been used in large solar telescopes to restore images of the Sun’s surface to their full potential, enabling telescopes to reach their theoretical diffraction limits—i.e., the theoretical maximum resolution of an optical system. These systems have since revolutionized observing the Sun’s surface, but until now, have not been useful for observations in the corona; and the resolution of features beyond the solar limb stagnated at an order of 1,000 kilometers or worse—levels achieved 80 years ago.
“The new coronal adaptive optics system closes this decades-old gap and delivers images of coronal features at 63 kilometers resolution—the theoretical limit of the 1.6-meter Goode Solar Telescope,” says Thomas Rimmele, NSO Chief Technologist who built the first operational adaptive optics for the Sun’s surface, and motivated the development.
Implications for the Future
Coronal adaptive optics is now available at the GST. “This technological advancement is a game-changer, there is a lot to discover when you boost your resolution by a factor of 10,” Schmidt says.
The team now knows how to overcome the resolution limit imposed by the Earth’s lowest region of the atmosphere—i.e., the troposphere—on observations beyond the solar limb and is working to apply the technology at the 4-meter NSF Daniel K. Inouye Solar Telescope, built and operated by the NSO in Maui, Hawaiʻi. The world’s largest solar telescope would see even smaller details in the Sun’s atmosphere.
“This transformative technology, which is likely to be adopted at observatories world-wide, is poised to reshape ground-based solar astronomy,” says Philip R. Goode, distinguished research professor of physics at NJIT-CSTR and former director at BBSO, who co-authored the study. “With coronal adaptive optics now in operation, this marks the beginning of a new era in solar physics, promising many more discoveries in the years and decades to come.”
The paper describing this study, titled “Observations of fine coronal structures with high-order solar adaptive optics,” is now available in Nature Astronomy.
The authors are: Dirk Schmidt (NSO), Thomas A. Schad (NSO), Vasyl Yurchyshyn (NJIT), Nicolas Gorceix (NJIT), Thomas R. Rimmele (NSO), and Philip R. Goode (NJIT).
Credit: Dirk Schmidt
About the U.S. NSF National Solar Observatory
The mission of the NSF National Solar Observatory (NSO) is to advance knowledge of the Sun, both as an astronomical object and as the dominant external influence on Earth, by providing forefront observational opportunities to the research community.
NSO built and operates the world’s most extensive collection of ground-based optical and infrared solar telescopes and auxiliary instrumentation— including the NSF GONG network of six stations around the world, and the world’s largest solar telescope, the NSF Daniel K. Inouye Solar Telescope—allowing solar physicists to probe all aspects of the Sun, from the deep solar interior to the photosphere, chromosphere, the outer corona, and out into the interplanetary medium. These assets also provide data for heliospheric modeling, space weather forecasting, and stellar astrophysics research, putting our Sun in the context of other stars and their environments.
Besides the operation of cutting-edge facilities, the mission includes the continued development of advanced instrumentation both in-house and through partnerships, conducting solar research, and educational and public outreach. NSO is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with NSF. For more information, visit nso.edu.
About the Big Bear Solar Observatory
The Center for Solar-Terrestrial Research (CSTR) at New Jersey Institute of Technology (NJIT) is an international leader in ground- and space-based solar and terrestrial physics, with interest in understanding the effects of the Sun on the geospace environment. CSTR operates, along with a number of other observatories, the Big Bear Solar Observatory (BBSO).
BBSO is located on the north side of Big Bear Lake in the San Bernardino Mountains of southwestern San Bernardino County, California, approximately 75 miles East of downtown Los Angeles. BBSO has a 1.6-meter clear-aperture Goode Solar Telescope (GST), which has no obscuration in the optical train. The telescopes and instruments at the observatory are designed and employed specifically for studying the activities and phenomena of the Sun. GST was the largest and highest-resolution solar telescope in the world for ten years, and is a leading facility for solar physics research.
The NSF National Solar Observatory and BBSO have collaborated for over two decades to develop and to advance adaptive optics technologies for solar observations. The GST has been a critical facility to develop and test prototypes for the 4-meter NSF Daniel K. Inouye Solar Telescope, which took over as the world’s largest solar telescope in 2022. GST’s first-ever coronal adaptive optics system Cona is the latest product of this successful and pioneering collaboration. For more information, visit bbso.njit.edu.
Contact
For media inquiries, please contact:
Evan Pascual
Communications Specialist
U.S. NSF National Solar Observatory
media@nso.edu
For technical inquiries, please contact:
Dirk Schmidt
U.S. NSF National Solar Observatory
dschmidt@nso.edu
