Polar Night explores the phenomenon of prolonged darkness in the Arctic and Antarctic, revealing its profound impact on polar ecosystems, wildlife adaptations, and human settlements. This seasonal event, lasting weeks or months, challenges life in unique ways, from disrupting circadian rhythms to influencing migration patterns. Understanding the polar night is crucial, especially considering the effects of climate change on these sensitive environments. The book delves into the science behind the polar night, differentiating between types of twilight and examining the physiological and behavioral adaptations of polar fauna. For instance, some animals modify their feeding strategies, while others rely on specialized sensory adaptations to navigate the darkness. Human settlements in the Arctic also face challenges, including seasonal affective disorder, prompting adaptations in architecture and cultural practices. Furthermore, the book highlights the hurdles faced by scientific research during the polar night, detailing how researchers employ specialized equipment and innovative techniques to study the atmosphere, ice, and ocean in extreme conditions. By drawing from peer-reviewed publications, firsthand accounts, and interdisciplinary research, Polar Night offers a comprehensive view of this frequently overlooked aspect of polar science, progressing from astronomical principles to the ecological and social impacts of prolonged darkness.