Our moon is on the move. Each year, it drifts an estimated 1.5 inches further away from Earth. And in the process, Earth’s rotation is actually slowing down. What if one night, the moon simply disappeared? Would we miss it?
A full moon is on average 14,000 times brighter than the next brightest night-sky object, Venus. So without it, every night would be as dark as a new moon. And star gazing would be spectacular.
But by the next morning, you’d begin to realize just how important the moon is for life on Earth. To start, between the sun, Earth’s rotation, and the moon, the moon has the largest influence on Earth’s tides.
Without it, high and low tides would shrink by an estimated 75%. This would jeopardize the lives of many types of crabs, mussels, and sea snails that live in tidal zones and disrupt the diets of larger animals who rely on them for food, threatening entire coastal ecosystems in the process. Within a few decades, we would start to see mass population declines in the sea and on land.
One of the largest spawning events in the world occurs in the Great Barrier Reef. Each November in the days following the light of a full moon, coral colonies across the reef — spanning an area larger than the state of New Mexico — release millions of egg and sperm sacs within nearly minutes of one another. Scientists are certain that the full moon plays a role in the timing, but exactly how remains a mystery.
On land, animals like these Red Crabs also use lunar cues to reproduce. After living most of their lives in the mountains, millions of adult crabs migrate down to shore. And then, only during the last quarter of the moon, females release their eggs into the sea.
Now, the moon may not hold as much sway over human reproduction. But without it, something else we care equally about would change — the weather. Tides and tidal currents help mix cold arctic waters with warmer waters in the tropics. This balances temperatures and stabilizes the climate worldwide. Without the moon, weather forecasts would be practically impossible. The average difference between the hottest and coldest places on Earth could grow to life-threatening extremes.
But none of this compares to the biggest change that we would have coming over the next millennia. Right now, Earth tilts on its axis at 23.5º mostly due to the moon’s gravity. If the moon disappeared, Earth’s axis would wobble between anywhere from 10 to 45º.
Some experts estimate that Jupiter could help keep Earth’s tilt from reeling completely out of control. But even just an extra 10º tilt could wreak havoc on the climate and seasons.
In the past, Earth’s tilt has changed by about 1-2º, which scientists think could have caused Ice Ages in the past. It’s hard to know what a 10º or 45º tilt would do but probably nothing good for most life on Earth.
The moon isn’t just imperative for life on Earth today. Experts believe that it may also have played a key role in the formation of life more than 3.5 billion years ago. Turns out, the moon isn’t just a beacon of light in the night sky. Its existence is crucial to the delicate balancing act that makes life here possible.
By Gene Kim and Jessica Orwig