Millions of Tons of Gas Hangs Over Our Star

By Phil Plait

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Posted Wednesday, Aug. 7, 2013, at 8:00 AM

I have got to get a solar telescope. Why? Because this:

The Sun boils with ionized gas in this image by Paco Bellido. Click to ensolarnate.
Photo by Paco Bellido, used by permission

That is a gorgeous shot of the Sun (which you really want to click to embiggen) taken by Spanish astronomer Paco Bellido on July 23. He was using a Coronado Solarmax telescope that was equipped with a special filter that shows warm hydrogen roiling on and above the surface of the Sun.

The image is inverted, so that dark material appears bright and vice versa. Long curls of filaments hang across the Sun’s face; megatons of hydrogen plasma suspended by our star’s powerful magnetic field. They really look three-dimensional, don’t they? Bellido made a red/green anaglyph version if you have the glasses for it, and that makes those filaments really pop out.

Sometimes filaments collapse back onto the Sun’s surface, and sometimes they erupt away. Alan Friedman, whose work has been on this blog many, many times, was observing the Sun on July 26 and caught one suspended without visible support above the Sun’s limb:

Another view, three days later, by Alan Friedman. Click to massively embiggen.
Photo by Alan Friedman, used by permission

In fact that hydrogen is trapped in the Sun’s magnetic field, so it was being supported (and, I’ll add, when a filament is seen against the backdrop of space it’s called a prominence). Friedman’s image is also inverted—he created a positive one for purists, too, if you'd like to see it. In the larger version of his picture you can see tremendous detail, but note that the Sun is about 1.4 million kilometers (860,000 miles) across, so something that looks small still dwarfs our entire planet! That filament you see wrapping around the Sun at the upper left is probably 300,000 km in length—almost enough to stretch from the Earth to the Moon.

I’ll note that we should now be approaching the peak of the solar magnetic cycle, when sunspots should be numerous and activity on the rise. However, the Sun hasn’t been holding up its end of the bargain; it’s still way below what we’d expect it to be doing. This whole cycle has been weird literally since it started, and I’m still not sure what the Sun’s going to do. Will it come roaring back, or will it continue to fizzle? Only time will tell