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Loss of the Night

Main Project Information
Goal Help scientists measure, understand effects of light pollution.
Task Use the free app to report which stars you can see
Where Global, anywhere on the planet

How many stars can you see where you live? The Loss of the Night App challenges citizen scientists to identify as many stars as they can in order to measure light pollution. The app is fun and easy to use, and helps users learn constellations as they contribute to tracking of how skyglow is changing over time.

Stargazing is a great activity for young scientists, but this ancient pastime has become increasingly difficult in growing urban areas. Help us understand light pollution, and learn about your own night sky!

You don't need to leave the city to take part. In fact, the app is designed specifically for use in very light polluted areas.

The more stars you observe, and the more often you run the app, the more precise the data for your location will become. As the seasons change so do the stars in the sky, and since there aren't that many very bright stars it is extremely helpful if urban users do measurements in each season.

A day after you have done an observation, you can examine your data at

Detailed instructions for Android:

Detailed instructions for iPhone:

How to Join

The app is available for Android:

and iPhone:

(If you don't have an Android or iPhone, take a look at the Globe at Night:

On a clear night, choose a location where you can see most of the sky, preferably away from bright glaring lights that will ruin your night vision. Urban parks, playgrounds, patios, and rooftop terraces are ideal. For safety's sake, go out as a group, and be sure to take care to choose a safe location where you won't trip or bump into something.

The sun needs to be far below the horizon (close to astronomical twilight) and the moon cannot be in the sky for researchers to analyze the data. If this isn't so, the app will warn you it's "not dark enough". You can do observations for fun, or you can wait a few days until the moon is no longer in the sky. Sunrise and moonrise times can be found using this calculator:

Around the time of the summer solstice, many users at high latitudes will never have astronomical twilight.

If the display on your phone doesn't seem to line up with the stars, your compass might need to be calibrated. There are compass apps on Google Play than can help you do this.

You can sign up for our project newsletter here:

Social Media
Android App URL
Ideal Age Group Elementary school (6 - 10 years), Middle school (11 - 13 years), High school (14 - 17 years), College, Graduate students, Adults, Families
Ideal Frequency Just once
Average Time Less than an hour
Spend the Time outdoors
Type of Activity At the beach, On a hike, At night, At home
Training Materials
Media Mentions
and Publications
Tags app, astronomy, atmosphere, citizen science, constellation, light, light pollution, night, nocturnal, pollution, sky, star, urban
Project Updated 08/10/2018