For the first time, scientists have captured detailed images of “coronal rain” — streams of cooled plasma falling back to the Sun’s surface — using a ground-based telescope in California.
These vividly colored images showcase both large arches of plasma and fine, delicate streams, providing the clearest view yet of the Sun’s outer atmosphere, known as the corona.
Coronal rain occurs when the superheated plasma in the corona cools and condenses, then flows downward along the Sun’s magnetic field lines. This phenomenon, along with solar prominences (large loops of plasma), was observed in the new images.
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The observations were made in hydrogen-alpha light and artificially colored pink. Time-lapse imaging technology was used to reduce the blurring effects caused by Earth’s turbulent atmosphere. The research was conducted by scientists from the U.S. National Science Foundation’s National Solar Observatory and the New Jersey Institute of Technology (NJIT), with their findings published in Nature.
“These are the most detailed observations so far, revealing features never seen before — and some that remain mysterious,” said Vasyl Yurchyshyn, a research professor at NJIT and co-author of the study.
The images were taken with the 1.6-meter Goode Solar Telescope at the Big Bear Solar Observatory (BBSO) in California, which recently installed an advanced adaptive optics system called Cona. This system uses laser technology to correct atmospheric distortions in real-time.
“Cona works like an enhanced autofocus for observing the sky,” explained Nicolas Gorceix, chief observer at BBSO. It adjusts a specialized mirror 2,200 times per second, significantly improving image clarity. While solar features smaller than 1,000 kilometers (620 miles) were previously difficult to observe from Earth, Cona allows scientists to study structures as small as 63 kilometers (39 miles).
The corona — Latin for “crown” — is one of the Sun’s most enigmatic regions. Typically hidden by the bright surface of the Sun (the photosphere), the corona is visible only during total solar eclipses. Despite being much less dense, it is hundreds of thousands of degrees hotter than the Sun’s surface, a long-standing mystery in solar physics.
Solar physicists focus on this area because it is the source of the solar wind, a steady flow of charged particles that can interact with Earth’s magnetic field, causing geomagnetic storms and stunning auroras.
Following successful testing at BBSO, the Cona system is now being installed at the Daniel K. Inouye Solar Telescope in Maui, Hawaii. This telescope, with a 4-meter aperture, is the largest solar observatory in the world and is expected to provide even deeper understanding of the Sun’s complex outer layers.
