What would happen if the moon was missing?

The Tweet: “If the earth didn’t have the moon, our days would only be 6 hours long.”

The moon is responsible for our current day length, and is making our days longer. About four billion years ago the day length was thought to be just six hours long, but the effect of the moon is slowing our rotation and eventually, if given enough time, the Earth will rotate at the same speed as the moon’s orbit.

Dr. Walter Robinson, a professor of marine, earth and atmospheric sciences at N.C. State, explains; “The spin is believed to have been about four times faster early in Earth history, such that days were only six hours long. Eventually, if the solar system lasts long enough, Earth’s rotation will become tidally locked to the moon, so that the length of one day will equal that of one lunar month.”

“Without the moon, Earth would spin faster, the day would be shorter, and the Coriolis force (which causes moving objects to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, due to Earth’s spin) would be much stronger,” he continues, “This would lead to air circulations in the atmosphere that might look more like Jupiter than what we see on Earth today – multiple east-west jet streams and likely more than one big gyre in the oceans.”

The effect of a missing moon on the evolution of life on Earth is impossible to imagine, but certainly if the moon disappeared tomorrow many species would be left in the lurch. It’s monthly cycle is intrinsically linked to life on Earth. Some species, mostly marine, use the moon to synchronise their body clocks in what is called a circalunar rhythm. The moon’s transit dictates the timing of breeding, spawning and movement for many marine worms, plankton and other species that are essential to marine ecosystems.

Remaining in the sea: the moon accounts for the majority of our tidal activity. The moon’s gravity is responsible for the high tide on the near side of the earth, with the resulting high tide on the far side, away from the moon, a result of the lower gravitational pull as the force from the moon weakens with distance. The sun exerts a smaller gravitational force on our sea, but there is still an effect, meaning that without a moon we would still have a tide, but a much smaller one. An entire ecosystem is dependent on the area of shoreline that is underwater at high tide and above water at low tide. This area is known as the intertidal zone and is home to many other species of marine life like crustaceans, molluscs and seaweed that make their home on our coastlines.

The light from the moon is also an important source for life on Earth. Some researchers think that moths navigate using the moon, although there is no agreement on this. But, nocturnal animals do need the moon to see at night. Despite having far more sensitive vision than daytime animals, they still need a light source to be able to see. No animal is capable of seeing in complete darkness.

Image: The Untweetable Truth

This post was first published on The Untweetable Truth (09/01/2014)

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