The outermost layer of the Sun
is called the corona or the crown. The corona is very
thin and faint and is therefore very difficult to observe from the earth.
Typically, we observe the corona during a total solar eclipse or by using
a coronagraph telescope which simulates an eclipse by covering the bright
The corona also emits energy of many different wavelengths, from long wavelength radio waves, to short wavelength X-rays. By designing special telescopes we are able to look at the corona in many different ways. Below is a picture of X-rays coming from our Sun taken by an X-ray telescope on the Yohkoh satellite currently orbiting the earth.
Solar Eclipse: HAO/NCAR
X-Ray Sun: Yohkoh Science Team