Recently, this image from NASA showing the sun looking quite a bit like a flaming Jack-o’-Lantern has been all over mainstream news outlets. Although the overall reporting has been accurate, if sparse on details, there have been a few instances where reports got things wrong. This article is meant to clear up any misconceptions and provide more details, including the source images, behind this provocative picture.
First, while it is true that NASA shared this image on social media a few days ago, the image itself is not new. It was actually captured by NASA’s Solar Dynamics Observatory (SDO) back on October 8th, 2014.
Secondly, if you could zoom in with your eyes on the sun, you would never see an image like this. That’s because this image was captured in ultraviolet wavelengths, which cannot be seen by the human eye. In particular, this spooky image was created by blending together two sets of extreme ultraviolet wavelengths at 171 and 193 Ångströms. Visible colors are assigned to these non-visible frequencies of light, in this case gold and yellow, so that we can see the image.
It is still a real image, not an artist’s rendering, although the color choices really does enhance the effect. In addition, the selection of wavelengths to include in the blend, as well as the contrast adjustment, make a big difference in the final image. (Source images for this composite image are at the bottom of this article.)
It shouldn’t be a surprise that an image of the Sun may resemble a jack-o’-lantern, given their basic circular shapes. It is a bit like looking at clouds, where you can spot various vague shapes quite easily if you look at enough of them. With the vast number of images of celestial bodies, it is no wonder that there are things like this jack-o’-lantern sun, as well as a Jack-o’-Lantern Nebula, galaxies that combine to look like a Menacing Face, and Pumpkin Stars.
Here are the source images at 171 and 193 Ångströms, as well as ones at other wavelengths that were not used in the flaming Jack-o’-Lantern composite image.