You can be a good steward of your night sky by measuring its brightness using this program. Bright skies mostly in cities are caused by light pollution generated from streetlights, big businesses and homes. Just go outside at least an hour after sunset when the moon is not up. Let your eyes adjust to the dark for about 10 minutes. Use your cell phone to visit app.globeatnight.org. Follow the instructions on that page and within a minute you have contributed to the tens of thousands of measurements made each year by citizen scientists from around the world. Globe at Night data recently found that light pollution is increasing by 10% per year on average around the world. You can make a difference by making measurements of the brightness of your night sky with this program. Thank you.