Imaging the Sun

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.)

Images at Various Wavelengths

Several observatories and satellites provide current imaging of the Sun. For example, the adjacent image was taken by the SOHO satellite on December 18, 1997, and shows the Sun in the light of ionized helium (in the UV at 304 Angstroms). Many surface features such as prominences, flares, granules, and spicules (that we shall define later) are apparent in this image.