limit commercial lighting to a specific curfew. Currently, there are no nationwide standards regarding light pollution. However, select cities across the United States and Canada are taking initiative to facilitate dark sky cities in order to reduce light pollution and view the night sky within city limits. Event dates See also Dark-sky movement Earth Hour National Astronomy Week Noctcaelador White House Astronomy Night Light pollution Bortle scale References External links > Environmental awareness days Awareness weeks 2003 establishments in the United States April observances Recurring events established in 2003 Unofficial observances Astronomy education events