Photograph by John McDonald
Looking roughly east-southeast from Mauna Kea, the fringes of the city of Hilo are seen on the left, with the lights of the village of Kea'au near the center of the picture. Beyond Kea'au, the lights of the Puna district are obscured (as they often are) by low clouds. The spectra of Kea'au and Puna are dominated by low pressure sodium lighting.
Prominent in this image is the planet Mars, which was near opposition at the time of this photograph. Its mostly continuum spectrum is dispersed in the lower part of the image. Another planet that showed up in this survey was Venus, extremely bright low in the east. These bright near-point sources of light do not contribute significantly to light pollution at Mauna Kea. However, in certain faint observations, the planets are actively avoided by astronomers using sensitive instrumentation.