What changes will occur on Earth as the moon moves further away from us? (continued)
Eric Kvaalen
Les Essarts-le-Roi, France
The moon moves away as it receives angular momentum around the Earth-moon centre of gravity, and that angular momentum comes from Earth, so Earth is slowing down. That is the main reason why we need to add “leap seconds” to the atomic clock time once in a while – the length of a second was defined using the length of a day around 1900, but a day is now slightly longer than it was then. As days get longer and longer over hundreds of millions of years, there will certainly be effects on the climate and weather. Days would become warmer and nights cooler. Tides would become smaller.
Advertisement
This process would go on until the length of a day and the length of a month would be equal, somewhat longer than a present-day month. If this happens (if the sun doesn’t expand and swallow up the Earth-moon system), there would still be tides, because of the sun. These tides would continue to slow down the rotation of Earth, so that the day would be longer than the month, and the moon would appear to move eastwards in the sky. The tides would now have the opposite effect from before, and would transfer angular momentum from the moon to Earth, drawing the moon closer to Earth and shortening the day.
Your tree will go on accumulating pairs of ancestors, but, gradually, most will all become the same pair
If this continues long enough, the moon would eventually get to the “Roche limit”, be broken up by the tidal force exerted by Earth and become a ring around Earth.
To answer this question – or ask a new one – email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
The use of AI tools (e.g. ChatGPT, Claude) to write either questions or answers is forbidden, and any submissions found to have been written using AI tools will be withdrawn.
