SKY QUALITY METER

A Sky Quality Meter (SQM) is the world's first economical light meter made only to measure how dark the sky is. Unlike meters used in photography, it was designed to work in low-light conditions. Manufactured in Canada by Unihedron, it measures a 45-degree patch of sky, and then reports the answer in units of star brightness (stellar magnitudes).  

The SQM is capable of very accurate readings, but care must be taken to screen out overly dark readings, which are easy to get and tempting to believe. Knowledge of the sky, independent confirmation, and repeatability are the secrets to high accuracy.

Because the SQM represents the sky as a single number—the "quality"—it is ideally suited to mapping the night sky on traditional maps of the earth. Simple maps can be made by writing the values measured on a map of where they were taken. Values can be color coded to make the map easier to read. GLOBE at Night is one of several excellent national student measurement programs that utilize this device.

The ability to represent the spaces around us on two-dimensional graph paper is an important spatial thinking skill most students have difficulty mastering. However, through real-world experience of a community that they are familiar with, they are well-prepared to create a map that make sense to them.

This type of class activity was the subject of a report by the National Academy of Sciences entitled Learning to Think Spatially. The report makes recommendations for how to teach children the important but nontraditional skill of spatial thinking. Only with a solid understanding of what a map represents can students use them to understand places they have never been.

The map produced in collaboration with the College of the Atlantic used sophisticated geographic information systems software to fill in the gaps between the measurement points. The result is a unique map of the entire Mount Desert Island from only 160 points.

Our education programs include an interdisciplinary student service-learning project utilizing the Sky Quality Meter.