Microwave and radio wave are the names given to light with wavelengths from about 1 millimeter (1 million nanometers) to more than 10 meters. (Compare that to the wavelengths of X-rays.) The Sun is the brightest source of radio waves in the sky.
Radio waves penetrate through the outer layers of solar gas, called the "chromosphere" and "corona". The depth to which the radio waves and microwaves can penetrate depends on their exact wavelength. The image here is constructed from microwaves with wavelength 1.7 centimeters. It shows us the structure of the Sun's atmosphere near the "transition region" between the chromosphere and the corona, about 2000-2200 km above the photosphere. If the Sun has spots today, you might be able to see bright active regions in this microwave image (active regions are associated with sunspots). Also you can sometimes see prominences -- great strands of gas that extend above the edge of the Sun.
Do the north and south poles of the Sun look any different from the rest of the Sun? If so, do they appear brighter or fainter? What about in the other solar images (like ultraviolet and X-ray)?
This radio image comes from the Nobeyama Radio Observatory, in Japan.