Historical eclipses provide useful data for measuring long-term changes in the rotation speed of our planet and can also be extrapolated to the future.
In the upcoming eclipse this Monday, the Moon will become the main attraction as it positions itself between North America and the Sun. This cosmic coincidence allows for a total solar eclipse due to the Moon being 400 times smaller than the Sun and also 400 times closer. However, the Moon is slowly moving away from the Earth at a rate of 3.8 centimeters per year. Eventually, this will result in the Moon being unable to cast a complete shadow on the Sun, with the last total solar eclipse predicted to occur in 200 million years. This prediction is based on chaos theory, which suggests that there are too many variables to accurately predict the behavior of the Earth-Moon-Sun system within the Solar System over such a long time frame. Solar eclipses offer a unique opportunity to observe the vastness of the cosmos and our connection to the Sun beyond just its light. During an eclipse, the shadow of the Moon travels across the surface of certain fortunate places on the planet. This alignment of the Sun, Moon, and Earth is a magical experience for those privileged to observe it. Historically, eclipses have played a significant role in human history. Ancient cultures were able to predict the dates and durations of eclipses, even though they did not understand their mechanisms. These predictions were often used as weapons of power in battle. Historical records of past eclipses have allowed scientists to measure the variation in the Earth’s rotation speed. It’s surprising to learn that the length of a day has not been constant throughout Earth’s history. Thanks to historical eclipses, scientists have discovered that the Earth’s rotation is slowing down, resulting in longer days. This information is crucial for investigating the processes contributing to the decrease in the Earth’s rotation speed over a long period of time. Spain will soon experience a trio of solar eclipses visible from most of the territory: two total eclipses in 2026 and 2027, and one annular eclipse in 2028. These events will be observed without fear, as we now understand their workings. The «Cosmic Vacuum» section presents our knowledge about the universe in a qualitative and quantitative manner. It aims to explain the importance of understanding the cosmos from a scientific, philosophical, social, and economic point of view. The section is integrated by Pablo G. Pérez González, a researcher at the Center for Astrobiology, and Eva Villaver, Director of the Space and Society Office of the Spanish Space Agency, and Research Professor at the Institute of Astrophysics of the Canary Islands.
