At how co-operative local institutions have been with preserving dark skies... (I believe it is safe to say that Mauna Kea has the highest density of world class scopes in the world, so we work hard to lobby for dark skies) All street lighting is done with sodium vapor lamps- dimmer than traditional lighting, and not broad spectrum... as a result, when I go out at night on the summit and look down at the towns, is that they are far dimmer than they would be without the various lighting measures taken... and when there is thick cloud cover below the summit you see NO light...

When the moon sets you not only can see the milky way, but you can see the darkness of the dust lanes that run along it...