What would have happened if our Moon had not existed? How would its absence have affected the Earth, its climate, and millions of living things on it? What would have happened if the Moon had been smaller or larger than its current size? Is the Moon a mass that coincidentally entered the Earth’s orbit?
It is possible to ask many more such questions. Astronomer Neil F. Comins, from Maine University, explained in his book, What If the Moon Didn’t Exist, the scenarios humankind would have faced if the Moon hadn’t existed. According to Comins, one of the millions of reasons why Earth is the only planet (known to us) to have life is the delicate balance between the Earth and the Moon. No occurrence in the universe is a coincidence, thus the Moon has been created as a balance factor. This balance is so sensitive that it is possible to say that there would be no life on Earth if it weren’t for the Moon.
The Moon, a sphere that has no atmosphere, and has a surface covered with craters, dust and rocks, is the Earth’s only satellite. The radius of the Moon is about one fourth of that of the Earth’s, its volume is about 1/50 of the Earth’s, and its mass is about 1/81 of the Earth’s. The Moon is around 240,000 miles from the Earth’s center and it takes 29.5 days to complete its orbit around the Earth. Even though we do not know for sure how the Moon came into being, the currently accepted theory asserts that a planet about 10 times lighter than the Earth, which astronomers call “Thiea,” crashed into Earth and a part of that planet broke apart and fell into space. This part (having lost its shape and most of its mass) crashed into Earth again after orbiting the Earth. In this second crash, the metal center of “Theia” fused into the center of the Earth while the outer shell’s light rocks scattered into space. In time, these little rocks fused to form the Moon. At first, the Moon orbited the Earth with a distance of only 14,000 miles, but in time this distance increased into an average of 240,000 miles.
The Moon’s largest effect on Earth is the tide. According to the law of universal gravitation, any two objects in the universe pull each other, and the force of this pull is in direct proportion to the objects’ masses and in inverse proportion to the square of the distance between the objects. The gravitational pull between the Earth and the Moon causes the seas and the oceans on Earth to either rise or subside. This effect is called the tide, which changes between high tide and low tide according to the Moon’s position. One third of all tide effects on Earth are caused by the Sun’s pull and the rest is caused by the Moon’s.
The Moon gets 1.57 inches farther from the Earth every year due to the tide. It is known that the time taken for the Earth to turn around its axis completely (1 day) increases by 0.02 milliseconds every year so that this distancing effect can be countered and the angular momentum of the Earth and the Moon can be sustained. It is also known that the time taken for the Earth to turn around its axis was 8 hours when the Moon was first created, and that it increased to 24 hours since then. If the Moon had not been created, there wouldn’t have been any tide and because of that, one day would still be 8 hours. That would mean that the Earth would be spinning around its axis about 3 times faster than its current speed. A greater spinning speed of a planet might mean stronger winds on its surface. For example, Jupiter and Saturn spin around their axes very fast and have about ten hours in a day. This causes winds with speeds up to 300 miles/hour at the east-west direction on their surfaces. The dust storms that occur in the atmospheres of these planets are caused by these winds and can be seen from the Earth with a telescope.
Without the Moon, the Earth would have spun faster, causing a faster heat exchange among the air, seas and land. This, in turn, would have caused hurricanes in the east-west direction on the face of the Earth with speeds up to 100 miles/hour. Such conditions would have been very inconvenient to all complex life forms including human beings. Even simple tasks like speaking or listening could have been very difficult or even impossible. Since a day would have been eight hours, this would have caused a mismatch between the biological clock of living things – including human beings – and the flow of the day, resulting in biological complications. Without the Moon, the high tide would have been very weak, again causing a very inconvenient environment for sea creatures.
The Moon also has a role in keeping the Earth’s axis at a 23.5 angle. It is known that the seasons result from this and allows the right amount of sunlight to the equator and the poles, creating a climate appropriate for life. Another known effect of the Moon on the Earth is that it reflects the Sun’s light and heats up the Earth by 32.36°F (0.2°C). The Moon also serves as a shield against space rocks, and if it had not been for the Moon many more rocks and meteors would have hit the Earth.
Most of the cosmic rays that come from space are neutralized by the Earth’s magnetic field. Few of these rays reach the Earth and causes chemical reactions. Without the Moon, the core of the Earth would have spun faster along with the Earth itself. With the core of the Earth spinning faster, the magnetic field would have been much stronger. This would have caused huge changes in the atmosphere. Besides, some bacteria and animals that use the magnetic field to find their way (such as sea turtles, salmon, eels, pigeons, and migratory birds) would have been negatively affected. Consequently, many ecosystems, as we know them today, would have been different.
Another significant service of the Moon to our lives is that, like the Sun, it has been used as a calendar throughout human history. Muslims today observe their Ramadan fast according to their hijri calendar which is based on lunar measurement of time.
The Moon is the largest satellite that we know, in proportion to the size of the planet it is attracted by (the Moon’s mass measures 1.23 % of the Earth’s mass). The size of the Moon plays a critical role in the sensitive balance of our ecosystem. When the relationship between the Earth and the Moon is examined carefully, one could easily conclude that the Moon has been created specially for the life on Earth by the One Who “has made the heavens high and set up the balance” with a gentle measure, a great cause and benefit, and was given to the service of humankind.