Astronomer: Astronomical observations in many areas have become useless because light from nearby cities obscures the stars Many people argue that since streetlights are needed for safety, such interference from lights is inevitable. Here in Sandsville, however, the local observatory' s view remains relatively clear, since the city has restricted unnecessary lighting and installed special street lamps that direct all their light downward. It is ttherefore possible to have both well-lighted streets and relatively dark skies. The astronomer's argument proceeds by ['offering a counter example to a general claim', 'proposing an alternative scientific explanation for a natural phenomenon', 'appealing to a scientific authority to challenge a widely held belief', 'making a distinction between terms']