The article explores the intriguing question of “how long was a day 500 million years ago,” addressing the search intent of readers interested in Earth’s historical timekeeping and geological changes. It provides a comprehensive overview of the factors that have influenced the length of a day throughout Earth’s history, including geological and astronomical processes. The content is informative and educational, aimed at readers who are curious about the evolution of time measurement on our planet. This article would be valuable for a webmaster looking to attract an audience interested in science, geology, or astronomy, as it combines historical context with scientific explanations.