A study has analysed the historical documents from the fourth to seventh century to reveal how Earth rotation has changed throughout the centuries.
Solar eclipse data that goes back to about 1500 years ago has helped to reveal the history of the rotation of the Earth. Shockingly, it has revealed how Earth rotation has changed within this short period of time and would add to worries about what may happen in the near future itself. The latest study in Publications of the Astronomical Society of the Pacific, Japanese researchers have studied the historical record from the Byzantine period and identified five solar eclipses seen around the Eastern Mediterranean, while highlighting their probable times and locations. Earlier, solar eclipse reports from this era were rare.
The data can be useful for understanding the variations in Earth’s rotation through time as eclipses can reveal information about our planet’s movement. However, because our ancestors did not record crucial details that modern astronomers need to know, it can be challenging to determine the precise dates, locations, and sizes of previous eclipses.
“Although original eyewitness accounts from this period have mostly been lost, quotations, translations, etc, recorded by later generations provide valuable information. In addition to reliable location and timing information, we needed confirmation of eclipse totality — daytime darkness to the extent that stars appeared in the sky,” Koji Murata, an assistant professor at the University of Tsukuba in Japan, said in a statement.
What has been observed from the ancient Solar eclipse?
The five identified solar eclipses from the 4th to 7th centuries in the Eastern Mediterranean region named – A.D. 346, 418, 484, 601 and 693, provided details about the difference in time measured according to Earth’s rotation and time independent of Earth’s rotation. This value is known as delta T, which shows the length of a day on Earth. The study has highlighted an example of an eclipse of July 19, 418 CE, which seems to be so complete that even stars appeared in the sky, and the site of observation was identified as Constantinople.
“The previous ΔT model for this time would have placed Constantinople outside the path of totality for this eclipse. Therefore, ΔT for the 5th century CE can be adjusted based on this new information,” the research mentioned.
The study added, “These new data shed light on variation of the Earth’s rotation on a centennial timescale, and thus help refine the study of other global phenomena throughout history, such as sea-level and ice-volume variability.”