What would have happened if the Earth did not have the Moon?

Gravity from the Sun also influences water levels on the Earth. The solar tidal bulges are about half the size of those caused by the Moon. Like the Moon, gravitational attraction to the Sun creates one bulge towards the Sun and one away from it. Unlike the Moon, solar tide*s do not vary on a daily basis. If there was no Moon, the daily tidal period would be exactly 24 hours. High tide would be at Noon and Midnight, and low tide at 6 PM and 6 AM every day. On a daily basis, we would still have large breakers on the continental west coasts because of the rotation speed of the Earth, and the existence of storms out at sea, and sloping beaches. The waves we are most familiar with from minute to minute are caused by small ripples out at sea caused by storms, which get amplified into majestic breakers by their motion up a sloping beach, and the rotation of the Earth from west to east which gives them added momentum. Without the Moon, we would still have high and low tides due to the Sun, but these would be half as tall as the lunar high and low tides. There would, however, be no Neap or Spring Tides which occur when the Sun and Moon are on opposite sides of the Earth, or on the same side.

So far as anyone can tell, there would be no impacts on the issue of life on the Earth because, if ocean tides were important in getting life started by, for example, mixing up the so-called 'primordial soup', the solar tides ought to have been more than adequate to have done the same thing 3.5 - 4.0 billion years ago.

Without the Moon, there would have been no necessity for breaking the calendar year into 12 months. A large body of music titles would also have disappeared.

The tidal stress upon the Earth due to the gravity from the Moon would have vanished, and some feel that this might have had an impact on how active the crust of the Earth would be in terms of vulcanism and continental drift. It is possible that the Earth would have been slightly less geologically active, and when the Earth's atmosphere was first being formed via volcanic outgassing, perhaps it would have taken a bit longer for the atmosphere to have reached high enough concentrations necessary for synthesizing life. I think, however, that the physics of the interior of the Earth, the rate of convection of the mantle, is far more under the control of non-lunar influences intrinsic to the Earth itself.

Without the Moon, there would be no 26,000 precession of the equinoxes which is due to the torquing of the Earth by the Moon. This would be replaced by a much slower precession caused by the influence of the Sun, Venus and Mars. The axis of the Earth's rotation in space would point towards the same spot in the sky for 100's of thousands and even millions of years.

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, and the impact that this could have had on the developing biosphere ranges from moderate to catastrophic. The Moon actually seems to stabilize the tilt of the Earth's rotation axis over the course of billions of years. Take a look at the axis tilts of the other solar system planets for which the masses of their moons relative to the planet's mass is even smaller than the Earth-Moon system.This is just a snapshot of what they are doing now, but consider that any one planet would experience extreme tilts far beyond our Earth's normal ranges.

Without the Moon, there might not be any seasons, or the seasons might be very different ones. It is believed that the Moon is an interloper from a more distant spot in the solar system which was captured by the Earth billions of years ago. This capture would have caused the rotation axis of the Earth to be seriously shifted to where it is now. The Earth may have started off with a rotation axis pointing almost perpendicular to the plane of the solar system, rather than canted at 23.5 degrees as it is now. Without this tilt, the rays from the Sun would always strike the Earth's surface at a fixed angle every day of the year. At the Earth's equator, the Sun's rays would always be perpendicular to the ground all year long. At a latitude of 45 degrees, they would strike the ground at 45 degrees every day, and at the North and South Poles, the Sun would never make it above the horizon.

Seasons would be dictated, not by time of year, but by your particular latitude on the Earth. There would be a belt around the equator where it always felt like summer. At mid-latitudes it would always feel like spring or autumn, and in the extreme latitudes we would have winter all year around. This would have significant effects on weather systems, circulation patterns etc.

Without the Moon, there would be no change in the length of the day due to the tidal friction between the Earth and Moon.

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