July 18, 2024
1 Solar System Way, Planet Earth, USA

Incredible photographs detail the Sun's 'fuzzy' surface

As the Sun approaches solar maximum, a host of phenomena dance across its surface. The chromosphere—the layer of the Sun between the photosphere and the corona—is filled with filaments, prominences, and spicules that give our favorite yellow dwarf an eerily velvety appearance. A pair of new photographs show these activities in detail, giving viewers a close-up look at the chromospheric turbulence that precedes the peak of solar cycle 25.

Most people in central Arizona do everything they can to avoid it. Sun This time of year, however, on July 2, Scottsdale astrophotographer Mark Johnston did the opposite. Just after sunrise, Johnston set up his hydrogen-alpha-modified 160-mm refractor telescope and pointed it at the Sun. Using a high-speed monochrome camera equipped to capture activity in the hydrogen-alpha wavelength, he snapped more than two thousand 10-millisecond images, each showing the Sun’s action-packed chromosphere in vivid detail.

“I was fortunate to have good seeing that morning, which is not common,” Johnston told ExtremeTech in an email. “When photographing the Sun or planets, it's critical that the atmosphere is calm and stable. Any turbulence can significantly reduce image quality. I take exposures of 10 milliseconds or less to help freeze the seeing. So I had the fortunate combination of interesting activity on the Sun and good seeing to capture it.”

A close-up image of the Sun's chromosphere.

Credit: Mark Johnston/@azastroguy

The images we see today are amalgams of about 200 of the best frames from each scene. Stacked on top of each other, these frames reveal an abundance of gaseous, energetic “texture,” giving the Sun a fuzzy appearance.

“The Sun is a fascinating target for astronomers because it's so dynamic,” said Johnston, who is also vice president of the Phoenix Astronomical Society and a NASA Solar System Ambassador. “The Moon, planets and stars are fun to look at, but they're essentially the same every time you look at them. Meanwhile, the plasma flow (on the Sun) creates beautiful arcs, spikes and other shapes.”

An example of this is found in the first image above, where a large prominence arches toward an airplane-shaped plasma clump. Below the prominence, plume-like spicules (jets of plasma that exit the photosphere at speeds of up to 109 kilometers per second) fill the chromosphere. In the second image, these spicules are seen in even greater detail along with filaments and sunspots, the latter of which appear in the photosphere but can be seen in less detail in the chromosphere.

The surface of the Sun is always changing, but the last few months have been marked by a peak periodThat's because Solar Cycle 25 is nearing its climax, when the Sun's magnetic poles will reverse, leading to an increase in sunspots and coronal mass ejections (CMEs). “The Sun has an 11-year cycle and we'll be hitting solar maximum later this year, so the activity level is high and will increase,” Johnston explained. “It's a great time to be observing the Sun!”

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