What would have happened to the Earth if there was no moon around? It is irrefutable that life would have sprouted and thrived on Earth even without the Moon, but things would be significantly different in detail. Some of them would be obvious, some would be a little more subtle, but there would be a great many impacts that we'd notice if we knew to look for them.

When you imagine Earth without a moon few things immediately pops up into our head. No beautiful, bright object traversing the night sky, hovering on the horizon, peeking through the trees on a cold winter's night. No romantic moonlight, no Blue Moon, and above all no lunar landing; that would have made Neil Armstrong's life less exciting.

However, on a little serious note it would be darker at night. If you've ever been outside on a totally moonless night, without any artificial light, you probably noticed two things. First, the night sky is absolutely breathtaking; you can see thousands upon thousands of stars with your naked eye alone. And second, you can't see a damned thing in front of your own face.

Furthermore, without the moon, Earth would spin faster. Our day would be shorter. Billions of years ago, Earth spun around on its axis much faster. But tidal stress slowed it down. Tides are caused by Lunar gravitation, that is greater on the side of Earth facing the Moon than it is on the centre of our planet. And its gravitational attraction on the centre of the Earth is stronger than on the opposite side of our planet. This makes ocean water bulge outward on either side of the planet. Because of the Earth's rotation this gives us high tides twice a day, followed by low tides about 6 hours later. This ebb and flow of the tides are what put the brakes on Earth's spin. If we'd never had a moon, we'd still have tides,due to sun, but they wouldn't be as strong. So, with no moon to slow it down, a day on Earth will become much shorter than our present-day 24 hours.

Thirdly, Earth rotates on its axis, tilted at about 23.5 degrees relative to its orbital plane around the Sun. Without this tilt, the rays from the Sun would always strike the Earth's surface at a fixed angle every day of the year. Hence, there would be no requirement of 12 months calender as either there would be no season change for a very long time or a dramatic change over the time like planet mars or mercury. The moon is sole reason behind this tilt.

When the Earth rotates it wobbles slightly back and forth on its axis. It's like a top, which doesn't simply spin in a vertical position on a table or the floor. But without the Moon we'd be wobbling much more. Moon actually stabilizes the earth's rotation. It's possible that Earth without a moon would wobble wildly, sort of like Mars does. The Red Planet's wobble is so extreme that it may be the cause of some cycles of climate change there. If the same thing happened here, Earth might wobble so much that seasons would become inhospitably extreme and Earth would be a much less stable and habitable planet. Without the moon the tilt of the Earth's axis could go from its current wobble of 22 to 25 degrees to a wide ride of zero to 85 degrees - zero would eliminate seasons, and 85 is basically the Earth leaning over on its side. If this happened, the current crisis we call global warming would be a very pleasant tea party by comparison.

Last but not the least, Without the Sun, Moon and Earth, there would be no eclipses. The Sun is constantly shining on Earth, casting a shadow for over a million miles (and over a million kilometers) in its wake. Yet without our Moon - just a few hundred thousand miles (or kilometers) away - there'd be no object that would pass through the Earth's shadow; there'd be no lunar eclipses. There'd also be no solar eclipses: no annular, partial, or total eclipses. The Moon's shadow is almost exactly equal in length to the Earth-Moon distance; without the Moon, no shadow, and no disc to block the Sun's disk. The next largest object that can pass in between the Earth (after the Moon) is Venus, and while it's incredibly cool when that happens, that's the closest we'd get to an eclipse without the Moon.