First Ultraviolet Image Of Our Sun Reveals Weird Web-Like Structures
Scientists have taken the first ultraviolet images of the Sun’s corona—its oddly hotter outer atmosphere—and found weird web-like structures.
Published in Nature Astronomy, the discovery was made after a scientist suggested pointing a special camera on a weather satellite to capture only the Sun’s ultraviolet (UV) light—the same light that creates Vitamin D.
The Sun’s corona is the outermost part of the Sun’s atmosphere, according to NASA, which is usually hidden by the glare from its surface. It’s thought to hold the secret to the solar wind, a stream of charged particles that the Sun pushes out into the solar system. On Earth this solar wind causes the aurora, but when severe it can also overload power grids, damage satellites and endanger astronauts.
“No one had monitored what the Sun’s corona was doing in UV at this height for that amount of time,” said Dr. Dan Seaton, Principal Scientist at the Southwest Research Institute (SwRI) and one of the authors of the study. “We had no idea if it would work or what we would see.”
For an entire month the Solar Ultraviolet Imager (SUVI) on NOAA’s Geostationary Operational Environmental Satellites (GOES) was pointed at either side of the Sun instead of directly at it.
The results were very exciting, with Seaton and his colleagues seeing elongated, web-like plasma structures in the Sun’s middle corona. It’s here that stored magnetic energy is released by the Sun, propelling particles into space.
“For the first time, we have high-quality observations that completely unite our observations of the Sun and the heliosphere as a single system,” said Seaton.
The Sun’s corona has been studied for the last quarter of a century by an instrument called LASCO on NASA’s Solar and Heliospheric Observatory (SOHO) spacecraft. However, LASCO can’t see the middle solar corona, where the solar wind originates.
“The origins of the solar wind itself and its structure remain somewhat mysterious,” said Seaton. “While we have a basic understanding of processes, we haven’t had observations like these before, so we had to work with a gap in information.”
This new study opens up a new approach to observing the corona on a large scale, said Seaton.
In April 2025, NASA will launch a spacecraft called PUNCH (Polarimeter to Unify the Corona and Heliosphere), a SwRI-led mission that will seek to image how the Sun’s outer corona becomes the solar wind.
“Now that we can image the Sun’s middle corona, we can connect what PUNCH sees back to its origins and have a more complete view of how the solar wind interacts with the rest of the solar system,” said Seaton.
The only time it’s possible to see the Sun’s corona from Earth is during a total solar eclipse, the next five of which will be:
- April 20, 2023: Western Australia, Timor Leste or West Papua
- April 8, 2024: Mexico, USA and Canada
- August 12, 2026: Iceland and Spain
- August 2, 2027: North Africa
- July 22, 2028: Australia
Wishing you clear skies and wide eyes.