Earth heading for 25-hour day as orbit slows? A study published in Proceedings of the Royal Society A: Mathematical and Physical Sciences looked at ancient and medieval eclipses from 720 BC to AD 1600 and times the Moon passed in front of stars between AD 1600 and 2015. The aim, to investigate the rate of the Earth’s rotation.
The Earth’s rotation is defined as the rotation of the Earth on its axis. The time it currently takes for the Earth to rotate once on its axis is 24 hours, a day.
Scientists have long known that the time it takes for the Earth to rotate on its axis is getting longer. This new study – co-authored by Durham University and the Nautical Almanac Office – has shown when, in the future, a day will be 25 hours long.
The length of a day is increasing at 1.8 milliseconds per century. This is slower than scientists previously believed – which was a rate of 2.3 milliseconds per century. At this rate, a day will be 25 hours long in around 200 million years.
The study’s authors looked at ancient eclipses and other celestial events which would have been visible from Earth – and where they would have been visible.
They then compared this with data available from ancient records. Discrepancies between expected position and real position showed the variation in the Earth’s rotation.
“It’s a very slow process,” Leslie Morrison, study lead co-author, told AFP, according to Phys.Org.
“These estimates are approximate, because the geophysical forces operating on the Earth’s rotation will not necessarily be constant over such a long period of time.
“Intervening Ice Ages, etcetera, will disrupt these simple extrapolations.”