The Moon is slowly moving away from Earth, and scientists can measure every inch

Earth and the Moon’s cosmic waltz is slowing down. Each year, our celestial neighbour drifts a little further into the deep expanse of space, moving away from us at about 1.5 inches per year. This tiny change is completely invisible to anyone looking at the night sky, but it is a major historic ledger for planetary scientists. Scientists are watching this slow drift and revealing dramatic stories of our planet’s ancient past, its changing climate and how the size of a single day has changed over billions of years.The mechanics of this planetary breakup are really an ongoing energy exchange. The Moon's gravity pulls on the Earth, causing bulges in the oceans. The Earth rotates faster than the Moon orbits. This means that the bulges get dragged slightly ahead of the Moon. This gives a gravitational tug forward, adding rotational energy to the Moon and increasing its orbit. Researchers explore cosmic secrets in deep-time geological records. Earth’s orbit was used to track ancient climate change in a seminal study in the Proceedings of the National Academy of Sciences, which analysed 1.4-billion-year-old marine sediments. Evidence like this can help scientists work out how much closer the Moon was and how fast our planet was spinning in the deep past.Fossil shells show shorter daysIf you go back in time, the moon hasn’t always been a distant fixture. It was born in a titanic collision of planets billions of years ago, when it was much closer to a youthful, fast-spinning Earth. To plot just how much our world has slowed down since those early days, scientists have looked to unexpected biological time capsules discovered at the bottom of ancient seas.Fossilised clam shells are an ancient calendar, a direct, daily record of growth. A key study published in Paleoceanography and Palaeoclimatology used high-resolution chemical analysis of Late Cretaceous rudist bivalve shells to calculate the exact number of days in a year. Around 70 million years ago, right at the end of the age of the dinosaurs, Earth made 372 rotations a year, not the 365 we have today, according to the research. This made a day only about 23.5 hours long, just as the astronomers had calculated. This proved that tidal friction had been gradually increasing the length of our days as the Moon gradually moved away. Modern oceans are pulledWhile the daily adjustments are tiny, the Moon’s slow drift still guides the natural cycles of contemporary life. The same force that pushes the Moon outward is responsible for the huge movement of our oceans.In coastal hubs like New York and Los Angeles, these tidal bulges change local water levels by as much as five feet, creating the high and low tides that determine coastal ecosystems and shipping lanes. While the Moon will never fully escape Earth's gravity, watching it slowly drift away gives scientists a natural laboratory in which to study planetary motion and the long-term effects of gravitational interactions. It's a quiet reminder that our planet is part of a dynamic, ever-changing system, where even a shell on a beach can tell us what the sky was like millions of years ago.