The moon used to be a mars-sized asteroid which incidentally collided with the Earth 4-4.5 billion years ago. Most of the mars-sized asteroid's debris joined the Earth through gravity. The leftover debris was charged into orbit with the Earth in a disk-like formation. Part of the Earth's mantle was also launched into orbit because of the collision. This whole process increased the Earth's mass dramatically. Over a long period of time, the debris that were orbiting the Earth, started to hit each other and clump together. This turned out to be our moon in the end that orbits us nowadays, although practically the same size it used to be much closer to the Earth.

    The moon happens to cause tides in the Earth by gravity, which help us in transportation, energy, and prevent large bodies of water to freeze, like lakes, etc. Although, we would still get tides without the moon, since we still have the Sun, it would not be much. Only 12 hours a day would we get different tides in one place, but since we barely have a delay time for different tides, which is at Quarter Moons every month. Also, the Sun is only 46% effective in creating tides on Earth, compared to the moon. So the moon contributes in creating tides twice as much as the Sun.

    The Moon also helps us obtain light even when we are not facing the Sun （this means nighttime）, by reflecting the light of the Sun back to Earth.

    One important factor about the moon is that it locks our planet into a stable rotation, and position with the sun. Resulting in the equator always facing the Sun to give balance to the temperature on the Earth. Planets that don't have large moons, rotate without stability. Where sometimes, the poles face the Sun and the equators do not. If that happens, the planet spin on the axis, of which the top is at the closest point to the Sun. That point will reach extreme high temperatures, since it constantly faces the Sun, whereas the opposite pole will be extremely cold half of the year. These extremes will exterminate all complex life on the planet. Due to drag between the Sun and the Earth, our moon is moving far from us, although slowly but surely. After we lose our moon, the Earth will not remain its stable position, sooner or later it will tip and all complex life will die. Life would still be possible, when the Earth returns back to it original position, life will start afresh. Although it is noted that since it will not have its stability, the Earth will wobble too, destroying life again and life will start anew every time, in a cycle.

    月球曾是一個(gè)體積與火星相當(dāng)?shù)男求w。而在40-45億年前，它與地球發(fā)生了巨大的撞擊。其大部分撞擊碎片因受引力影響，被地球合并，地球的質(zhì)量因而大大增加。余下的，則是一個(gè)似圓盤(pán)狀的星體，并圍繞地球旋轉(zhuǎn)。此次撞擊中，地球部分表層亦被激射出去，在太空中繞地球旋轉(zhuǎn)。這些撞擊碎片，經(jīng)年累月之后，逐漸互相粘合到一起，形成一個(gè)星體，而這個(gè)星體，就是今天我們所熟知的月球了。而它的體積，在撞擊前曾經(jīng)和地球相差無(wú)幾。

    月球通過(guò)自身的引力，給地球帶來(lái)潮汐。這使得我們?cè)谶\(yùn)輸、能源方面大受其益；且湖泊等大型水體也因此不致被冰凍。誠(chéng)然，沒(méi)有月亮，地球也會(huì)因太陽(yáng)而有潮汐，但是，要小很多了。一天每12個(gè)小時(shí)，我們便可在同一個(gè)地方看到不同的潮汐。每個(gè)月，上弦月或下弦月時(shí)，不同的潮汐都會(huì)如期而至。此外，太陽(yáng)在引起潮汐方面，其效率只有月球的46%.換言之，月球貢獻(xiàn)的潮汐，有太陽(yáng)的兩倍之多了。

    月球?qū)Φ厍蛑辆o要的，是使地球的自轉(zhuǎn)得以穩(wěn)定，而對(duì)太陽(yáng)的位置亦保持恒常。因此，赤道總能正對(duì)太陽(yáng)，地球的溫度便能達(dá)到均衡。一個(gè)恒星，如沒(méi)有體積合適的衛(wèi)星，那么它的自轉(zhuǎn)會(huì)極不穩(wěn)定。這樣的行星，有時(shí)會(huì)以南或北極面對(duì)太陽(yáng)，而非赤道。試想如果行星以南或北極正對(duì)太陽(yáng)的轉(zhuǎn)軸自轉(zhuǎn)，那么一極會(huì)因始終正對(duì)太陽(yáng)而溫度極高，而另一極則會(huì)在半年中極度寒冷。如此極端的溫差，會(huì)導(dǎo)致地球上的高級(jí)生命難以生存。由于太陽(yáng)和地球之間有牽引力，月球正離我們不斷遠(yuǎn)去，只是過(guò)程十分緩慢。一旦當(dāng)我們失去月球，地球?qū)㈦y以保持自轉(zhuǎn)軸的穩(wěn)定，地極遲早會(huì)傾向太陽(yáng)，高級(jí)生命將不復(fù)存在。當(dāng)?shù)厍蚧謴?fù)的合適位置，生命又將重生。而由于地球的位置不是持久穩(wěn)定的，生命又會(huì)被摧毀。生命的生滅會(huì)不斷上演