What if the Moon didn't exist?
12 August 2013, 18:00 PM
UPDATED
12 August 2013, 20:46 PM
APPROXIMATELY 4.4 billion years ago, a Mars-sized object called Theia collided with the Earth, blowing out a huge chunk of matter that eventually became the Moon, our "light in the nocturnal sky." The glancing collision caused the Earth to spin faster about its axis and day-night cycle decreased from 8 hours to 5 hours.
For centuries, many myths have been woven about the Moon. She is an Arctic Sea Demon to the Inuit, a Changing Woman to the Navajo, "Chand Mama" to a Bangali, and "a friend for the lonesome to talk to." Women appeal to the Moon for fertility and calendars follow her motion. Lovers court each other under a full moon while others are believed to morph into werewolves.
What if Theia did not collide with the Earth? What would Earth be like without the Moon? What would life be like on a moonless Earth?
The most obvious effect of the Moon is tides – a consequence of the gravitational pull exerted on Earth by the Moon. A moonless Earth would still have tides due to the Sun's gravitational pull. But the Sun being 390 times farther away from us than the Moon is, tides will at most be one-third as high.
Tidal friction slowed down Earth's rotational period from 5 hours 4.4 billion years ago to 24 hours today (TDS 5-21-13). Without the Moon, the Sun-induced tidal friction would not be strong enough to slow down the Earth to its present rate of rotation. Instead, a day now would be 8 hours long and a year will have 1,095 days.
Our biological clock that regulates sleeping, walking, eating, and other cyclic activities is based on a 24-hour day. Faced with an 8-hour day, these circadian rhythms would be hopelessly out of sync with the natural world.
Due to moonless Earth's rapid rotation, we will be subjected daily to gale force winds with speed in excess of 100 miles per hour. Hurricanes and tornadoes would have even higher wind speeds. Trees with shallow root systems will be easily knocked down by the strong winds. Tree-dwelling life would have a difficult time surviving, since tall trees would sway more wildly. Clearly, birds battling the ever present winds do not seem to be a likely bet on a moonless Earth, nor do naked apes.
With continuous high winds, ocean waves would be enormous and perpetual. Under these circumstances, amphibians would certainly be pulverized to a pulp rather than being able to sedately walk onto land and then back into the water.
Obviously without the Moon there will be no eclipses or moonlight. Cloudless nights will be dark and star-filled. Nocturnal animals would, therefore, be less successful in hunting, foraging, and traveling.
The Moon acts as a stabilizing force keeping the tilt of the Earth's rotational axis to 23.5 degrees with respect to the perpendicular to its orbital plane. The tilt makes the Earth habitable with moderate seasons and prevents temperature extremes. Without the Moon, the tilt would wobble between 85 and 90 degrees. This would make the Sun shine almost directly above one of the poles for half of the year, making the length of a day and the summer season almost equal.
Additionally, the rapidly rotating Earth will be unstable to the extent that the poles would periodically flip. This flipping would create enormous stress on the Earth's geology leading to catastrophic earthquakes, volcanic activity, and tsunamis. Such a planet would be incomparably inhospitable to life.
We are what we are today because of the challenges faced by our progenitors. An Earth without a Moon would clearly provide challenges of its own. But given enough time, complex form of life would probably evolve.
What would be different about life on a moonless Earth compared to life on Earth today? Since creatures evolving there would have to withstand the perpetual pounding from winds and debris they carry, animals including humans with turtle-like shells or rhino-like skins are perhaps one solution.
The writer is a Professor of Physics at Fordham University, New York.
APPROXIMATELY 4.4 billion years ago, a Mars-sized object called Theia collided with the Earth, blowing out a huge chunk of matter that eventually became the Moon, our "light in the nocturnal sky." The glancing collision caused the Earth to spin faster about its axis and day-night cycle decreased from 8 hours to 5 hours.
For centuries, many myths have been woven about the Moon. She is an Arctic Sea Demon to the Inuit, a Changing Woman to the Navajo, "Chand Mama" to a Bangali, and "a friend for the lonesome to talk to." Women appeal to the Moon for fertility and calendars follow her motion. Lovers court each other under a full moon while others are believed to morph into werewolves.
What if Theia did not collide with the Earth? What would Earth be like without the Moon? What would life be like on a moonless Earth?
The most obvious effect of the Moon is tides – a consequence of the gravitational pull exerted on Earth by the Moon. A moonless Earth would still have tides due to the Sun's gravitational pull. But the Sun being 390 times farther away from us than the Moon is, tides will at most be one-third as high.
Tidal friction slowed down Earth's rotational period from 5 hours 4.4 billion years ago to 24 hours today (TDS 5-21-13). Without the Moon, the Sun-induced tidal friction would not be strong enough to slow down the Earth to its present rate of rotation. Instead, a day now would be 8 hours long and a year will have 1,095 days.
Our biological clock that regulates sleeping, walking, eating, and other cyclic activities is based on a 24-hour day. Faced with an 8-hour day, these circadian rhythms would be hopelessly out of sync with the natural world.
Due to moonless Earth's rapid rotation, we will be subjected daily to gale force winds with speed in excess of 100 miles per hour. Hurricanes and tornadoes would have even higher wind speeds. Trees with shallow root systems will be easily knocked down by the strong winds. Tree-dwelling life would have a difficult time surviving, since tall trees would sway more wildly. Clearly, birds battling the ever present winds do not seem to be a likely bet on a moonless Earth, nor do naked apes.
With continuous high winds, ocean waves would be enormous and perpetual. Under these circumstances, amphibians would certainly be pulverized to a pulp rather than being able to sedately walk onto land and then back into the water.
Obviously without the Moon there will be no eclipses or moonlight. Cloudless nights will be dark and star-filled. Nocturnal animals would, therefore, be less successful in hunting, foraging, and traveling.
The Moon acts as a stabilizing force keeping the tilt of the Earth's rotational axis to 23.5 degrees with respect to the perpendicular to its orbital plane. The tilt makes the Earth habitable with moderate seasons and prevents temperature extremes. Without the Moon, the tilt would wobble between 85 and 90 degrees. This would make the Sun shine almost directly above one of the poles for half of the year, making the length of a day and the summer season almost equal.
Additionally, the rapidly rotating Earth will be unstable to the extent that the poles would periodically flip. This flipping would create enormous stress on the Earth's geology leading to catastrophic earthquakes, volcanic activity, and tsunamis. Such a planet would be incomparably inhospitable to life.
We are what we are today because of the challenges faced by our progenitors. An Earth without a Moon would clearly provide challenges of its own. But given enough time, complex form of life would probably evolve.
What would be different about life on a moonless Earth compared to life on Earth today? Since creatures evolving there would have to withstand the perpetual pounding from winds and debris they carry, animals including humans with turtle-like shells or rhino-like skins are perhaps one solution.
The writer is a Professor of Physics at Fordham University, New York.
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