Our Moon is unique among the observed celestial bodies within our solar system. There is no other satellite closer in size and composition to its host-planet (if one excludes the dwarf planet Pluto), and the Earth-Moon system is the only tidally locked pair.
Besides the obvious; no moonlit walks, no “Moon River” and no Apollo Moon landings, how would life without the Moon affect us here on Earth?
Bye Bye Tides
For starters, the Moon’s absence would leave us (mostly) without tides. The Moon’s gravity tugs on the planet. This tugging pulls on the Earth’s oceans which creates the tides. Tides are pretty important. “They helps transport heat from the equator to the poles,” says Bruce Bills, a geodynamicist at the NASA Jet Propulsion Laboratory in Pasadena, Calif. “Without the lunar tides, it’s conceivable that climate oscillations from the ice age to the interglacial would be less extreme than they are. Such glaciations caused migrations of animal and plant species that probably helped speed up speciation.”
The Need For Speed
Without the Moon, the Earth would also rotate much faster, causing a more turbulent atmosphere. As a result, we would experience unending gales of life-hostile, skirt-blowing winds. As the Moon’s orbit slowly creeps away from the Earth at 1.5 inches per year, her gravimetric drag will eventually slow the Earth’s rotation to match the pace of the Moon’s orbit. One day will be 9,600 hours long, and the Moon will only be visible from one hemisphere. Of course, by then the sun should be in an expanding red-giant phase, slowly engulfing its planets. The sun’s coronal atmosphere could be creating drag against the Moon, slowing it toward an eventual breakup as Earth’s gravity tears it apart. But by then, the Earth’s surface will be uninhabitable due to the scorching heat.
Recent computer simulations suggest that, without the Moon, the Earth’s axis tilt may have been very different than what it is today. This would have caused very different seasons on the Earth. The impact of having radically different seasons would have had on the developing biosphere ranges from moderate to catastrophic. The Moon helped to stabilize the tilt of the Earth’s rotation axis over the course of billions of years and can be thanked for our summer, winter, spring and fall seasons.
The Earth would be a very different place without our Moon. Life as we know it on our planet may not have existed without it.