Choosing a Star Sign for the Trail Stamp Station

A Sign Beside the Trail Stamps

High on a mountain trail, hikers stop at a wooden cabinet to stamp their trail cards. A volunteer team wants to add a science sign beside the cabinet. The sign will ask, “Why does the Sun look so much brighter than other stars?” Before choosing a design, the team gathers evidence and tests a model. Their goal is to choose an explanation that fits both the model results and information about stars.

The team's fact cards say that the Sun is a star. Its distance from Earth is about 150 million kilometers. The next nearest star is more than 40 trillion kilometers away. A trillion is a million million, so these distances are very different. Stars also differ in how much light they produce. Some stars produce more light than the Sun, although they look much fainter from Earth. The team does not have measurements of the light produced by each star.

To explore one part of the problem, the team uses a small battery-powered lamp inside a shaded trail supply room. They place a light meter facing the lamp, measure the distance, and record how much light reaches the meter. They repeat this at one, two, and three meters. They keep the same lamp, brightness setting, room lighting, and direction of the meter. Nothing blocks the light. Distance is the part they change. The graph shows their readings, rounded to whole numbers. Lux is a unit used by the meter; a larger reading means more light reaches it.

The meter measures light arriving at its position, not the total light the lamp produces. The lamp stays switched to the same setting throughout the test. This model is small enough to use safely, but its distances are not the enormous distances between Earth and stars. The volunteers will use the test as evidence, not as a full-sized copy of space. They do not look directly at the Sun during this project.