The Bortle Scale Visibility Estimator is a tool designed for stargazers to assess the quality of the night sky based on the Bortle scale. This scale, developed by John E. Bortle, categorizes the night sky's brightness and quality, helping astronomers and casual stargazers alike to determine the best locations for observing celestial events. The estimator takes into account two main factors: the inherent brightness of the sky, rated from 1 to 9, and the level of light pollution in the area, rated from 0 to 100. By inputting these values, users can calculate a visibility score that indicates how favorable the conditions are for stargazing. A lower score indicates better visibility, while a higher score suggests poor conditions due to light pollution. For optimal stargazing experiences, it is recommended to find areas with low light pollution and high Bortle ratings. For more information and resources on stargazing, visit darkest-hour.com.