If you need another reason to believe Low Pressure Sodium Lamps are Best, here's one from Wikipedia:
For locations where light pollution is a consideration, such as near astronomical observatories or sea turtle nesting beaches, low-pressure sodium is preferred... Such lamps emit light on just two dominant spectral lines (with other much weaker lines), and therefore have the least spectral interference with astronomical observation.
Sodium lamps - better for turtles, better for seeing stars.