Billions of years ago, an Earth day was less than 13 hours long. Today, our days are getting slightly longer, thanks to the Moon. This change is due to the way the Moon interacts with our oceans, affecting our planet's rotation. This fascinating relationship has important implications for life on Earth.
The Moon's gravity creates ocean tides, which, in turn, affect Earth's rotation. As Earth spins, the Moon's gravity pulls on the oceans, creating a bulge that moves slightly ahead of the Moon. This causes friction, slowing down Earth's rotation. The energy lost by Earth is transferred to the Moon, causing it to move further away at about 1.5 inches (3.8 cm) per year.
This process means that Earth's days are slowly getting longer. Since the 1600s, the length of a day has increased by about 1.09 milliseconds per century. While this change is tiny each year, it adds up over billions of years.
In the past, the Moon was much closer to Earth. Around 3.2 billion years ago, the Moon was only 270,000 km (170,000 miles) away, compared to 384,400 km (238,855 miles) today. This made days shorter, with two sunrises and two sunsets every 24 hours, possibly affecting early life on Earth.
The Moon's distance from Earth hasn't always increased at the same rate. The shape and size of our oceans play a role. For example, the current size of the Atlantic Ocean enhances tidal forces, speeding up the Moon's retreat. This will change as Earth's continents continue to shift.
Recent studies also suggest that changes in Earth's inner core might slightly affect day length. The core's rotation has slowed down, possibly influencing Earth's rotation and adding to the complexity of this process.
The lengthening of Earth's days is a result of the Moon's influence. This relationship between the Moon and Earth shows how dynamic our planet is. While the changes are too small to notice in our daily lives, they remind us of the intricate connections in our world. The Moon may be drifting away, but its impact on our planet's rhythms and life continues to be profound.