Every other Friday, the Outside/In team answers a listener question about the natural world. This week we’re answering some pretty imaginative questions about the moon.
Kathryn, from Portland, OR, asked, “What if [Earth] had no moon?” and Mande, from Lake Villa, IL, asked “What if [Earth’s] moon was much larger.”
What would happen if the moon disappeared?
If we made the moon disappear, well…things would be different, to say the least.
I spoke to Stephon Alexander, a theoretical physicist at Brown University. “Without the moon,” Alexander said, “the Earth’s tilt would be destabilized, and therefore it [would] probably completely mess up the seasons.”
To understand why, it helps to remember that the Earth’s axis is tilted at about a 23.5-degree angle. This is what gives us our seasons. But with no moon, sometimes Earth could be a straight 90 degrees, which would eliminate seasons completely, and other times it could just lie flat on its side, which would make the poles burning hot and the equator freezing cold.
The tides would also be affected, but they wouldn’t disappear completely. That’s because the sun’s gravity would still create tides, albeit smaller ones. This would impact wildlife, like sea turtles, that lay their eggs with the tide.
Alexander said even land animals could be impacted. “If you don’t have light at night, predators will have a harder time spotting [prey].” Predators like pumas, owls, and sharks could have a harder time hunting, although there are studies that show just the opposite: that some predators do better without moonlight, like lions.
What if Earth’s moon got much larger?
On the other end of the spectrum, if the moon was more massive, low tides would be lower, and high tides would be higher. “You might have waves that are as large as apartment buildings,” said Alexander.
A heavier moon could also make the earth tilt even more, said Alexander, which would make seasonal extremes and weather more intense. Plus, in order for the moon to maintain its orbit around Earth, it would either have to revolve around Earth faster, in which case the lunar calendar would speed up, or the moon would slowly get pulled in and crash into Earth.
So, whether we disappear the moon, or we make it bigger, either way it could very well end life on Earth as we know it.
The moon is the moon we’ve got
“So much of the cycles of the moon modulate the physiology of living beings on Earth, including, I believe, humans,” Alexander said. Biologists have found, for example, that the reproductive cycles of sea creatures align with the lunar cycle. There are even studies on the moon’s impact on human sleep patterns and menstrual cycles, though the latter claim has been called into question.
At the end of the day we can imagine a moonless world, or a bigger moon. But all we can say for certain is that our moon looms large in life as we know it.
Submit your question about the natural world to the Outside/In team. You can record it as a voice memo on your smartphone and send it to outsidein@nhpr.org or call the hotline, 1-844-GO-OTTER.
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