Is light pollution a serious problem for astronomical observations?
Yes it is, for optical astronomy. It is well known that only the brightest stars are visible from a city, whilst from very dark places like the ESO sites in Chile it is even possible to see your shadow cast by the brightest stars on a clear moonless night. While visible light pollution does not disturb astronomical observations in other bands of the electromagnetic spectrum such as radio waves, radio astronomy can be affected by terrestrial signals emitted at the same frequencies as those detected by the telescopes.
