It is the pull of the Moon's gravity on the Earth that holds our planet in place. Without the Moon stabilising our tilt, it is possible that the Earth's tilt could vary wildly. It would move from no tilt (which means no seasons) to a large tilt (which means extreme weather and even ice ages).
The moon influences life as we know it on Earth. It influences our oceans, weather, and the hours in our days. Without the moon, tides would fall, nights would be darker, seasons would change, and the length of our days would alter.
If the moon disappeared, the oceans would have smaller tides. This in turn will affect water organisms like crabs, mussels, starfishes and snails as they depend on the tides for survival. This impact on the coastal ecosystem will lead to an imbalance in the food chain and eventually cause mass extinctions.
If the moon disappeared, Earth's axis would wobble between anywhere from 10 to 45º. Some experts estimate that Jupiter could help keep Earth's tilt from reeling completely out of control. But even just an extra 10º tilt could wreak havoc on the climate and seasons.
The Latest
The brightest and largest object in our night sky, the Moon makes Earth a more livable planet by moderating our home planet's wobble on its axis, leading to a relatively stable climate. It also causes tides, creating a rhythm that has guided humans for thousands of years.
A boon for life
The gravitational pull of the moon moderates Earth's wobble, keeping the climate stable. That's a boon for life. Without it, we could have enormous climate mood swings over billions of years, with different areas getting extraordinarily hot and then plunging into long ice ages.
What would have happened on Earth if, about 4.5 billion years ago, Theia had passed peacefully on its way without striking Earth and forming a moon? Well, life of some sort would probably exist on Earth, but humans almost certainly wouldn't.
Before Earth and the Moon, there were proto-Earth and Theia (a roughly Mars-sized planet). The giant-impact model suggests that at some point in Earth's very early history, these two bodies collided.
The political tug-of-war over NASA's mission and budget isn't the only reason people haven't returned to the moon. The moon is also a 4.5-billion-year-old death trap for humans and must not be trifled with or underestimated. Its surface is littered with craters and boulders that threaten safe landings.
With no sunlight, photosynthesis would stop, but that would only kill some of the plants—there are some larger trees that can survive for decades without it. Within a few days, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after.
In about 50 billion years, the Moon will stop moving away from us and settle into a nice, stable orbit. At this point, the Moon will take about 47 days to go around the Earth (currently, it takes a little over 27 days). When this new stability is achieved, the Earth and the Moon will be tidally locked to each other.
If Earth were to stop spinning but continue to orbit the sun, a "day" would last half a year, and so would the night. It could warm up much more during the day and cool down much more during the night. This would affect the climate on Earth.
Hence, it's possible that there was a stage of our planet's history that the researchers dubbed “Purple Earth”. That time would date somewhere between 2.4 to 3.5 billion years ago, prior to the Great Oxygenation Event, which was likely due to the rise chlorophyll-based photosynthesis.
At more temperate latitudes, the rings would look like a giant arch, crossing from one end of the sky to the other. These glittering rings would neither rise nor set, and would always appear in the exact same place in the sky. These cosmic landmarks would be visible both day and night.
Right after its formation, the Moon was extremely hot. Its entire outer surface was a deep “magma ocean” of molten rock. It would have glowed a dull red in Earth's skies, looking 15 times as wide as the Moon did today.
NASA says microbial life may exist in the harsh environment of the lunar south pole. Once thought to be inhospitable and devoid of life, scientists are now considering the possibility that lifeforms could exist on the Moon.
The average composition of the lunar surface by weight is roughly 43% oxygen, 20% silicon, 19% magnesium, 10% iron, 3% calcium, 3% aluminum, 0.42% chromium, 0.18% titanium and 0.12% manganese. Orbiting spacecraft have found traces of water on the lunar surface that may have originated from deep underground.
We'd watch our lakes and water supplies dwindle a little more every year until nothing was left. Humans might survive for a while near our homes. We still would have access to groundwater and might get some underground hydroponic farms working. But on the surface, plants and animals would begin to dry out immediately.
While the Lunar surface is hostile to life as we know it, a deep Lunar biosphere (or that of similar bodies) cannot yet be ruled out deep exploration would be required for confirmation.
To date, no proof of past or present life has been found on Mars. Cumulative evidence suggests that during the ancient Noachian time period, the surface environment of Mars had liquid water and may have been habitable for microorganisms, but habitable conditions do not necessarily indicate life.