Revisiting light pollution

A few weeks ago, I posted a pretty nifty map of light pollution everywhere on Earth.  At the time, I lamented the tragic loss of our night skies as a resource of natural beauty.  Now that I have a few down minutes here at Kitt Peak National Observatory, I also want to point out the damaging effect this light pollution has on scientific research.  Kitt Peak is about sixty miles from the city of Tucson.  Between here and there is mostly empty desert, so you might think that the sky here would be pretty darn dark.  And, for the most part, you'd be right.  Compared to what most Americans and Europeans have ever seen, the skies here probably seem shockingly dark.  The Milky Way, a sight seldom seen anymore, is clearly visible overhead.

Tuscon as seen from Kitt Peak.  Click to enlarge the image.  (Image Credit: NOAO/AURA/NSF)

The problem is, "pretty darn dark" doesn't cut it for astronomical research.  Every bit of stray light is damaging to the observations which are vital to astronomy.  And, all things considered, Kitt Peak is in a pretty remote location.  Are there any high, dry sites in the continental United States more than sixty miles from a major city?  Maybe, but not many.  And the sprawl of modern cities ensures we'll probably never use them.  Take a look at the image accompanying this post.  See how much the lights of Tucson spread in just 25 years?  That sort of expansion makes the substantial expense of setting up an observatory a risky proposition.

Because of this, new telescopes are being built only in a handful of the remaining high, dry, dark places left: mainly Hawaii and Chile.  Fortunately, the power of the internet means that such facilities are remotely available to an increasingly-large part of the scientific community.