The Sun at other Wavelengths

The Sun emits light primarily in the visible spectrum, but it also emits at other wavelengths, as illustrated in the following figure.

(Recall that the visible part of the spectrum extends from about 4000 Å up to about 7500 Å in wavelength.) The following false-color images show the Sun at X-Ray and UV wavelengths.

The X-Ray image was taken in 1992 with the Yohkoh Soft X-ray Telescope (SXT). Since X-Rays are normally emitted from objects having temperatures of millions of degrees, this indicates that such hot spots occur in the Sun's upper atmosphere and corona. It is not completely understood why the Sun is producing the broad diffuse X-Ray glow seen in this image (more info). Here is the most recent Yohkoh image, and here is an MPEG movie (about 100 kB) of SXT observations for the last month.

The UV image was taken by the Solar and Heliospheric Observatory (SOHO). It is sensitive to the light emitted by highly charged iron ions at high temperature. In the image, lighter regions are at temperatures of about 1 million degrees, while darker regions are somewhat cooler (more info).

Current Solar Images at Various Wavelengths
Here are current solar images in various wavelength bands: where, for example, the notation Fe XII (195 Å) denotes imaging in the light of a 195 Angstrom transition in the +11 charge state of iron (chemical symbol Fe, ionization state 12, with the neutral atom denoted Fe I).