Wolfram Cloud Document

If you looked at the Sun today through a properly shielded telescope, you would see a rather bland surface. No major sunspots or groups are visible.

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ResourceFunction["SolarImage"][ImageSize->600]

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But optical wavelengths can be misleading. The interesting stuff often appears when you observe in ultraviolet (UV) and X-rays. Here’s a current image of the Sun at 211 Angstroms.

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ImageAdjust[ResourceFunction["SolarImage"][12,ImageSize->600]]

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Notice those large dark areas around the Sun. Those are not sunspots, which are relatively small and localized. The large dark areas are coronal holes. These are areas where the solar atmosphere, or corona, shows gaps allowing unobstructed windows into deeper solar layers. The solar wind coming from these regions is like a gusty wind, but it takes time for those effects to reach Earth. Since this is a UV image, the color is purely artificial.

Although we are observing in extreme UV wavelengths, there are multiple bands within the UV range and we can substitute various bands for the red, green, and blue images we are used to observing with the naked eye. The following takes the 335, 211, and 193 Angstrom images and substitutes them for the red, green, and blue channels respectively in a combined image to give us a false color image spanning multiple wavelength bands.

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{r,g,b}={ResourceFunction["SolarImage"][14,"BlendColors"->{Black,Red,White},ImageSize->4096],ResourceFunction["SolarImage"][12,"BlendColors"->{Black,Green,White},ImageSize->4096],ResourceFunction["SolarImage"][11,"BlendColors"->{Black,Blue,White},ImageSize->4096]};

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ImageResize[ImageAdjust[ImageAdd[{r,g,b}]],600]

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In the next few days, its expected that the solar wind speed will increase as a result of these coronal holes. At the time of this post, the solar wind speed is nearly 400 km/s.

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