Sky glow is a problem for astronomers because it obscures the sky so that they cannot identify stars and other celestial forms. Astronomers need clear skies to do their work well. Sky glow adds brightness to a part of the sky that becomes impenetrable except with radio telescopes. Another name for sky glow is light pollution. It is an orange-colored glaze seen at night over cities.
Another problem is that once the sky glows, it continues to glow. Changes in the glowing do not occur. A cloudy sky can clear for the next day, but sky glow never goes away once it is there. Unless the astronomer already lives in a rural area, he must travel to get away from it.
Neighbors can also cause sky glow but not shading their lights. This can happen at campgrounds even in the mountains - turning a dark night into a light-filled disaster for the astronomer.
Sky glow covers the most distant points of light so that constellations are incomplete. The glow makes some celestial objects disappear completely so the astronomer loses his orientation.
Obscurity already exists from volcanic ash and other natural factors in the universe. The obscurity changes the effectiveness of the telescope's power to see. It only takes a 10% increase in sky glow to distort the telescope's performance.
Cities could correct sky glow if they would use lights other than neon lights at night. Halogen lights produce more light pollution than other type lights. To reduce some light pollution, people can install shades around their lights to direct the light downward instead of into the night sky where it breaks up and scatters.
Low pressure sodium lamps provide less light pollution than other types of lamps. Observatories tend to use sodium lamps more than other types of lamps. These come in both high and low pressure. For astronomers, low pressure gives off less sky glow.
When observing the stars, any other light except the light coming from the stars causing the star to "twinkle." Steady light is what makes stargazing enjoyable.
Astronomers also know that on the nights when the moon is full, seeing the stars is difficult in the section of the sky where the moon glows. Sky glow is light from the cities which do the same thing.
To escape sky glow, astronomers head for the mountains and rural settings where the cities lights do not cause the glow. The dark sky gives off points of light that they can identify. Sometimes they have to travel at least fifty miles to get away from the city lights.