1.0planet forward//www.getitdoneaz.comnational science foundation//www.getitdoneaz.com/author/nationalsciencefoundation/ rich600338<blockquote class="wp-embedded-content" data-secret="hvvapmkli9"><a href="//www.getitdoneaz.com/story/controlling-light-pollution/">controlling light pollution</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="//www.getitdoneaz.com/story/controlling-light-pollution/embed/#?secret=hvvapmkli9" width="600" height="338" title="“controlling light pollution” — planet forward" data-secret="hvvapmkli9" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script type="text/javascript"> /* <![cdata[ */ /*! this file is auto-generated */ !function(d,l){"use strict";l.queryselector&&d.addeventlistener&&"undefined"!=typeof url&&(d.wp=d.wp||{},d.wp.receiveembedmessage||(d.wp.receiveembedmessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-za-z0-9]/.test(t.secret)){for(var s,r,n,a=l.queryselectorall('iframe[data-secret="'+t.secret+'"]'),o=l.queryselectorall('blockquote[data-secret="'+t.secret+'"]'),c=new regexp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentwindow&&(s.removeattribute("style"),"height"===t.message?(1e3<(r=parseint(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new url(s.getattribute("src")),n=new url(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeelement===s&&(d.top.location.href=t.value))}},d.addeventlistener("message",d.wp.receiveembedmessage,!1),l.addeventlistener("domcontentloaded",function(){for(var e,t,s=l.queryselectorall("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getattribute("data-secret"))||(t=math.random().tostring(36).substring(2,12),e.src+="#?secret="+t,e.setattribute("data-secret",t)),e.contentwindow.postmessage({message:"ready",secret:t},"*")},!1)))}(window,document); /* ]]> */ </script> new measurements of the nsf-funded kitt peak national observatory near tucson, ariz., show that sky brightness has remained remarkably constant over the past 20 years, despite the area’s rapid population growth. the study demonstrates that with a conscientious effort, human-caused light pollution can remain constant, despite large population growth in cities. shielded outdoor lights, required...