Ancient shell shows days were half-hour shorter 70M years ago
I disagree with assumption that year length has stayed constant the past 70 million years. The Earth experiences tidal friction from the Sun just like the Moon and Earth affect each other. I am guessing the year lengthening effect slower than month &amp; day lengthening because Suns tidal force is a third of Moons.<p>In addition Earth year may have changed during the Great Solar System Reconfiguration Event when Jupiter and the other gaseous planets hypothesized to have migrated outwards from orbits closed to the Sun. This may have happened 3.8 billion years ago causing increase of craters on the terrestrial planets at that time.<p><a href="https:&#x2F;&#x2F;www.nasa.gov&#x2F;topics&#x2F;solarsystem&#x2F;features&#x2F;young-jupiter.html" rel="nofollow">https:&#x2F;&#x2F;www.nasa.gov&#x2F;topics&#x2F;solarsystem&#x2F;features&#x2F;young-jupit...</a>