Palomar Mountain was originally chosen as the site for the Observatory
because it was far away from any large cities, so the glare from
artificial lights would not drown out the faint signals from faraway stars and
galaxies. In the last 50 years, however, the rapid growth of San
Diego, Escondido, and other nearby communities have greatly added to
this light pollution, and the Observatory is at risk of being unable
to continue many key types of research. This
animation (Quicktime, 900 Kb) illustrates how the
increase of light
pollution over time makes the night sky harder and harder to see --
not only for astronomers working at Palomar, but for everyone all over
the Southern California region. Fortunately, there are a few simple precautions which we can all take, which not only help reduce light pollution, but also make more efficient use of our limited energy reserves and result in lower electricity bills:
- Use the minimum amount of outdoor lighting required for the task.
- Shield lights to prevent any direct upward illumination.
- Turn lights off when they are not needed.
- Use low-pressure sodium lights wherever possible. These lights cause the least interference with the observatory.