[dylukes]

San Diego is near the Palomar Observatory and Mount Laguna observatory (see map [1]). The observatory as well as environmental concerns of bright lighting at night messing with wildlife is why San Diego in most zones at night uses what appear to be Low Pressure Sodium (LPS) lighting. See also [2] for the current code.

However, over time these LPS streetlights started to be replaced by Induction lighting. And as of 2016, the new standard is LED based, which is supposedly even better for light pollution [3].

In areas where sea turtles nest, LPS lighting is still preferred, as it is very different from the white light from the moon they use to navigate [4].

One nice consequence for residents: as a result of the strict light pollution regulation, and the consistently clear skies, most nights one can see a surprisingly large number of stars in the sky for an urban city environment. Nothing close to a clear night far north or out in the desert, but still more stars than you might expect.

---

You can read more about it here:

[1] https://www.sandiegocounty.gov/content/dam/sdc/pds/docs/pds2...

[2] https://www.sandiegocounty.gov/pds/docs/LightPollutionCode.p...

[3] https://www.sandiego.gov/sites/default/files/12-14-16-adopti...

[4] https://conserveturtles.org/information-sea-turtles-threats-...

[jayknight]

Thanks, this is way more interesting than I thought!