06-03-2025

Astronomers capture high-definition details of the Sun's corona with new technology

Earth.com staff writer

For generations, the Sun’s corona – the bright, outermost layer of the Sun’s atmosphere – has captivated the interest of scientists.

Visible only during a total solar eclipse, the corona holds mysteries about extreme heat, violent eruptions, and swirling prominences. Yet Earth’s turbulent atmosphere has made it difficult to capture sharp images of this fiery halo, until now.

Using an innovative adaptive optics system, scientists have removed the blur that has long blocked a detailed look at the Sun’s outer layer.

A new adaptive optics system

The team’s work introduces a system called coronal adaptive optics, or “Cona.” Installed at the 1.6-meter Goode Solar Telescope (GST) in California, Cona was funded by the NSF and is operated by NJIT’s Center for Solar-Terrestrial Research (CSTR) at the Big Bear Solar Observatory (BBSO).

“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,” said Dirk Schmidt, NSO Adaptive Optics Scientist.

Cona’s success has led to the clearest images and videos of fine structures in the Sun’s corona to date.

Raindrops and a solar prominence

Among these new observations are movies showing stunning details: a solar prominence rapidly reshaping itself, turbulent plasma flows, and the collapse of delicate plasma streams.

“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,” said Vasyl Yurchyshyn, NJIT-CSTR research professor.

“It is super exciting to build an instrument that shows us the Sun like never before,” Schmidt added.

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. Credit: NSO — 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. Click image to enlarge. Credit: NSO

Another highlight captures coronal rain, which is plasma that is cooling and falling back to the Sun’s surface.

“Raindrops in the Sun’s corona can be narrower than 20 kilometers (12 miles),” These images are the sharpest yet of coronal rain.

“These findings offer new, invaluable observational insight that is vital to test computer models of coronal processes,” NSO Astronomer Thomas Schad remarked.

Cracking the mysteries of the Sun’s corona

The corona is puzzlingly hot – millions of degrees hotter than the Sun’s surface. Scientists don’t fully understand why. It also hosts cooler plasma that is visible during eclipses as a soft, reddish-pink glow.

Studying these cooler regions at small scales could hold the key to solving the mystery of coronal heating. It could also improve predictions of solar eruptions, which can disrupt satellites and power grids on Earth.

At the heart of Cona is a mirror that reshapes itself 2,200 times per second to cancel out the blurring effects of atmospheric turbulence.

“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,” BBSO Optical Engineer and Chief Observer Nicolas Gorceix explained.

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. Credit: GST/NSO — 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. Click image to enlarge. Credit: GST/NSO

Adaptive optics have been used since the early 2000s to sharpen images of the Sun’s surface, helping telescopes achieve their theoretical resolution limits. But until now, these techniques couldn’t be applied to the Sun’s corona.

For decades, the sharpness of coronal images stalled at about 1,000 kilometers (620 miles) – technology comparable to what was available 80 years ago.

“The new coronal adaptive optics system closes this decades-old gap and delivers images of coronal features at 63 kilometers (39 miles) resolution – the theoretical limit of the 1.6-meter Goode Solar Telescope,” said Thomas Rimmele, NSO Chief Technologist.

Next steps for solar astronomy

Cona is now fully operational at the GST, offering an unprecedented boost in resolution. “This technological advancement is a game-changer, there is a lot to discover when you boost your resolution by a factor of 10,” confirmed Schmidt.

The research team is already planning the next step: applying this technology to the NSF’s 4-meter Daniel K. Inouye Solar Telescope in Maui, Hawaiʻi. As the world’s largest solar telescope, it could reveal even smaller details of the Sun’s atmosphere.

Philip R. Goode, distinguished research professor of physics at NJIT-CSTR and former BBSO director, highlights the broader significance.

“This transformative technology, which is likely to be adopted at observatories world-wide, is poised to reshape ground-based solar astronomy,” he said.

“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,” he added.

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Thanks to researchers from the U.S. National Science Foundation’s (NSF) National Solar Observatory (NSO) and New Jersey Institute of Technology (NJIT), a clearer view is finally possible.

Click here to watch videos of the Sun from the Goode Space Telescope…

The full study was published in the journal Nature Astronomy.

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