Moons orbit planets, planets orbit the sun. Round and round they go forever locked in gravitational harmony. Sunrise, sunset, new moon, full moon, every day a 24 hour certainty. Foundations so fundamental we take them for granted. Not so fast – days haven’t always been 24 hours. Truth is, days are getting longer.
New astronomical research dubbed astrochronology suggests that recently as 1.4 billion years ago Earth completed a day in 18 hours. Science credits interaction of Earth/Moon tidal forces for lunar orbit spiraling away from Earth at 1.5 inches a year.
Gravity is a cosmic wonder, proximity of mass dictates rate of rotation. 18 hour day Earth was driven by a vastly closer Moon. Over time rotation slows as the Moon spirals away. Less pull, less spin, longer days.
Credit: NASA/Goddard/Arizona State University