The DIY TESS-W Photometer Measures Light Pollution in the Night Sky

If you’re in a remote part of the world and the weather is clear, then the night sky will be completely awash with millions of stars that make you feel as though you’re looking at the very fabric of the galaxy. But if you live in or near even a modestly-sized city, then you can likely only see a few stars at night. That’s mostly due to light pollution, though smog can have an effect as well. The TESS-W is a DIY photometer designed to measure that light pollution.

The TESS-W was created as a low-cost way to conduct light pollution studies. Those studies could potentially be used to enact change and ultimately reduce light pollution — a cause that all amateur astronomers can appreciate. That change could be reducing the number of city lights, or switching to different kinds of bulbs that are less bright or are simply a different color. For any of that to happen, however, there needs to be an affordable way to collect data about localized light pollution across the world.

The TESS-W accomplishes that with an ESP8266 paired with a host of sensors and housed within a weatherproof enclosure. The primary sensor is a TSL237 light sensor for measuring the sky’s brightness. There is also an infrared thermometer module for detecting cloud cover. The TESS-W even has a built-in heater to reduce lens condensation and melt snow or ice that builds up. The ESP8266’s WiFi capabilities allow for easy data collection. While this project does utilize a custom PCB, it may be worth building one yourself if you want to help collect data on light pollution.